Guide to Windows Dual Boot

At one time, there was only Windows and only one
Windows, Windows v3. Now there are Windows, plural: Windows 95, Windows 98,
Windows NT, Windows 2000, and Windows Me. What's more, the possibility exists
that you, as a power user, have more than one copy of Windows -- or
more than one type of Windows -- on one machine.

Having multiple installations of Windows on one computer is
called dual booting or multiple booting. Windows NT and 2000 are designed to be
installed in conjunction with other operating systems, especially Windows
95/98/Me. Windows 95/98/Me are not: When you install them on a PC, they want to
be the only OS on that PC.

Is there any way around this? Yes; in fact, there are many
possibilities. This article will step you through how to get the various
versions of Windows to coexist with each other on the same PC. Over the
years, Windows has grown slightly more tolerant of having more than one
installation of itself in a given PC -- especially NT and 2000
-- but a number of scenarios aren't supported at all by Microsoft
and require a little coaxing or, in some cases, trickery.

You can take several paths to achieve multiple booting. These
depend on what's already installed in your computer, how many hard drives and
partitions you have, and whether or not you're amenable to (or capable of) using
third-party programs to control boot choices. If your machine is sufficiently
powerful enough (500MHz or better and at least 128MB of RAM), you also have the
option of using an emulation system such as VMware to run your other
OSes.

First, you need to verify which OS you're currently running,
and which OS you want to add to your system. If you're adding Windows 95, 98, or
Me to a machine running Windows 2000 or Windows NT, that's the most complex
scenario. Because it's also the scenario about which we've received the most
correspondence from our readers, we'll address it first.

Adding Win NT or 2K to a machine running either Windows 95,
98, or Me is actually much easier, because both NT and 2K are designed to
coexist to a high degree with other operating systems. Some pitfalls may be in
store, but we'll cover them in the following pages.

Install 95/98/Me on a NT/2000
PC

Installing Windows 95, 98, or Me
on a Windows NT system is probably the most difficult of the scenarios listed
here. The reason is fairly simple: Windows 95/98/Me wants to be the only OS on a
given computer, and will take steps to insure that nothing else can boot
up.

If you have Windows NT already installed on the computer (on
a FAT partition), for example, you'll get a warning during the Win95/98/Me
installation process about the presence of NT system files. If you have an NTFS
partition, Win95/98/Me will report it as being damaged and won't let you do
anything about this except abort the installation, since it doesn't let you
interactively repartition your disk during setup.

If you have NT/2K on a FAT partition and install Win95/98/Me
on it anyway, any NT/2K boot files will be erased, and the boot sector will be
replaced with a Win95/98/Me edition. Win NT/2K, however, has repair tools to
address this problem, which we'll discuss in detail later.

Here are the steps for adding a Win95/98/Me installation to a
Windows NT machine.

1. Ensure your NT PC has Service Pack
6a.
Windows NT, in an out-of-the-box installation, has problems that can
cause serious disk corruption if you're using a drive larger than 2GB (and who
isn't these days?). Before doing anything else at all, make sure you have
patched the system with the latest Windows NT Service Pack plus whatever
hotfixes are relevant to your computer. With Windows 2000, you can patch with
Service Pack 1, but it's not required, since it comes 95/98/Me-aware out of the
box.

2. Make a Windows NT/Windows 2000 repair disk.
Repair
disks in Windows NT/2K are floppies, created with a system utility, that contain
copies of key Registry entries as well as a description of the partition
geometry of the disk. If either of those things gets damaged, you can rebuild
them to an extent. A repair disk is one of those underrated Win NT/2K features
that can often save you when you least expect it. If you make a mistake during
this process, you won't regret having it.

To build a repair disk in Windows NT, use the RDISK.EXE
command-line utility. Just run it and follow the prompts. In Windows 2000, run
the Backup utility and click the Emergency Repair Disk button on the Welcome
tab.

3. Prepare a FAT partition.
Windows 9x can't install onto
anything other than a FAT or FAT32 partition. FAT, also referred to as FAT16, is
the original partition format used by DOS and, later, Windows 95. Windows 98
introduced FAT32, a revised version of FAT that could support bigger partition
sizes and was more reliable. But NT supports only FAT, so you need to have a FAT
partition with enough free space for Windows 9x to be installed. FAT32 cannot be
read or written by a Windows NT machine.

To be scrupulously honest, it's possible to have Windows NT
read and write FAT32 partitions with a third-party utility. However, if you want
your system to be as reliable as possible, we don't recommend using such a
method.

	(click to expand view)
	Only FAT16 or FAT32 partitions, not NTFS, can support a Windows 95/98/Me installation. FAT16 provides the best cross-compatibility with other operating systems.

The partition in question doesn't have to be the primary boot
partition in the computer, but it must be a DOS-accessible partition for the
installation to succeed, and the bootable partition in the system must be FAT.
If there's no such spare partition in the system, you will have to make one
using a third-party tool such as PartitionMagic. Windows doesn't support the selective editing
of partitions and neither does Windows NT, for that matter!

You can use the same partition that holds Windows NT itself,
but we don't recommend it for two reasons:

1) You must not use the same directory name for both
operating systems. This actually varies by default: NT installs in \WINNT, and
Windows 9x installs in \WINDOWS. However, if NT were installed in \WINDOWS for
whatever reason, it would create problems, and some applications stupidly expect
Windows to be installed in \WINDOWS and nowhere else.

2) The \Program Files directory is used by both operating
systems to hold apps that are installed by default -- everything from IE to
Solitaire. Because some of these apps are OS-specific -- some are
specifically for NT that aren't for 9x and vice versa -- you may
wind up breaking one OS's default app set if you install it on top of the other.
This alone is reason not to install both OSes on the same partition, since the
\Program Files directory can't be easily redirected during the install
process.

Preparing a partition in Windows NT is done through the Disk
Administrator utility. Right-click in the listed free space on a drive and
choose Create; right-click in the same space again and choose Commit Changes
Now; then Format.

4.
Create a Windows 9x boot floppy.
Sure, you're always supposed to have a boot
disk handy, but more often than not, you don't. For dual booting, you'll
definitely need a Windows 9x boot floppy disk. Find a PC running Win9x and a
blank floppy disk. You'll be preparing a bootable floppy disk that will have
nothing on it save the command-line version of Windows, which is basically, DOS.
To do this, boot Win 95/98/Me and run the following command-line operation:
FORMAT A: /S with a blank floppy in drive A:.

From the \Windows\Command directory, copy the SYS command to
the A: disk as well.

NOTE: Don't mix and match OSes here. If you're installing
Windows 95, don't use a Windows 98-prepared boot disk. It won't work. Windows
95, 98, and Me all practice pretty stern revision control over their own
internal files and utilities.

5. Copy Win98 installation files onto the hard drive.
With
Win NT running, insert the Windows 98 CD-ROM and copy the contents of the \SETUP
folder onto an available FAT partition. Use the same folder name unless a folder
named SETUP is already there. If it is, try a folder name such as
NewSetup.

6. Boot with the floppy; then run the install files from hard
drive.
Put the prepared boot floppy in your A: drive and reboot. Once you've
booted into command-line Windows (DOS mode), type "SYS C:" to transfer the boot
files. The command should return the statement "System
transferred."

Switch to the \SETUP folder you copied over and run
SETUP.EXE. Windows Setup should begin the install process.

As we mentioned before, you're going to get a warning about
Windows NT system files being present (or a generic warning about files from
another OS, depending on what else may be in your computer) when you go through
the install process. Ignore this for now, as we'll be back later to take care of
it.

The installation process for Windows 98 should not vary
greatly from the way you would normally set it up. The one major difference
needs to be the location of the Windows installation; it can't be on the same
partition with your NT install, or your \Program Files folder will contain
inconsistent copies of some programs.

Once the installation finishes, make sure your system boots
correctly into Windows 98 before continuing. If Windows 98 refuses to boot,
unrepaired disk problems may have occurred during
Setup.

7. Repair your
Windows NT boot files.
Once Win98 is in and running, the last step is to
repair the Win NT/2000 boot files. This will allow you to use the NT boot loader
to choose between NT/2K and Windows 9x.

Repairing the boot files is fairly automatic. Boot the
Windows NT/2000 setup disks -- or the CD-ROM, if you can boot
CD-ROMs -- and select R in Setup to repair. Choose to repair only
the Windows NT boot sector -- nothing else. Note that if your
Windows NT/2K installation can't be found, you should pop in the repair disk you
made (you DID make one in step 2, correct?) and use that to help the repair
program find your installation.

Once the repair operation is finished, boot the computer to
see whether you get the Win NT/2K boot options menu with a new entry at the
bottom for Windows 9X. Usually you will. If not, you'll need to add a line to
the file BOOT.INI, which should be a read-only file in the root directory of
your boot drive. You'll need to modify the file's permissions so that it's not
read-only in order to change it.

	(click for expanded view)
	Editing the BOOT.INI file is easy enough -- use Notepad or another plain-text editor -- but you'll need to turn off the file's read-only attribute before you can save it. Also be careful not to edit anything except the reference to Windows 95/98/Me

Add the line:
C:\="Windows 95"

to the bottom of the BOOT.INI file, and reboot. The comment
in quotes can be anything you like, as long as it's distinct from the other menu
choices.

The next time you reboot your system, simply choose the
appropriate selection from the boot menu to boot either Win 95/98/Me or
NT/2K.

Install NT
on a Win2000 PC

Adding Win NT to a Win2000 PC should in some ways
be treated like adding Win95/98/Me to a Win NT/2000 installation. The main
reason for this is, on the whole, that NT cannot recognize Win2000 NTFS
partitions (unless you have Service Pack 6A, and even then it seems to have
problems). Win2000's edition of NTFS contains some features, such as changes to
how permissions work, that are not entirely backwards-compatible with WinNT. The
best thing to do is place NT on a separate partition, where it can use its own
version of NTFS.

You'll also need to repair Win2000's boot files, just to be
safe. The process for doing this is identical to the repair process in Windows
NT.

Install NT/2000
on a 95/98/Me PC

Adding Windows NT or Windows 2000 to a machine
that already has Windows 95, 98, or Me on it is much simpler than the reverse
for one simple reason: Windows NT/2000 is smart enough to detect the presence of
another operating system during installation and modifies its boot files
accordingly. Because of this, if you install WinNT/2000 in a machine that
already has another version of Windows on it -- and it doesn't
matter what version -- you'll see an entry in the boot manager for
both editions of Windows.

The installation procedure to follow when adding NT/2000 to a
95/98/Me computer isn't enormously different from installing NT/2K in general.
There are, however, a few guidelines to follow.

1. Do not install NT on a FAT32 partition.
This is
probably the single most important rule. NT supports only FAT and NTFS, not
FAT32, and can't be installed on a FAT32 partition. In fact, it generally can't
even read FAT32 partitions. So if you're planning to make data readable by both
operating systems, be sure not to place it on a FAT32 partition. Place shared
data either in a FAT partition or on a networked drive.

Also, do not convert a FAT16 partition that has NT installed
on it. Converting a partition with NT installed on it to FAT32 will render it
unbootable.

The sole exception to this rule is with Windows 2000. Win2K
can read and write FAT32 partitions without problems. Installing Win2K on a
FAT32 partition, however, means you won't be able to use NTFS security features
on your system partition.

2. Don't use disk compression.
In fact, this is a global
rule: Never use disk compression on any multiple booting system. It's not worth
it, and it creates more problems than it solves. Most drives today are big
enough that disk compression is contraindicated, anyway. Windows Me won't even
install onto a system that has disk compression running.

3. Do a disk check before an installation. Lingering
disk errors can cause terrible problems later on down the line when you install
an operating system. During Windows installation, there's a disk check; don't
skip this step.

4. Always use a discrete partition for other operating
systems. As with installing Win 95/98/Me on an NT/2K system, this rule
also applies here, and for the same reasons. Installing one Windows application
set over another can cause horribly unpredictable things to happen. In most
cases it will break IE and Outlook Express, and if shared .DLLs are overwritten,
it may cause other apps to malfunction, too.

(click for expanded view)
Each operating system should always reside on its own partition for the best possible results. Here, a FAT32 partition has been prepped for a new installation of Windows Me.

If
you want to share applications between operating systems, the best way to do
this is to install the app on one OS, boot the other OS, and then reinstall it
into the exact same folder. However, a few applications may not work correctly
if you do this: for instance, any application that uses CTL3DV2.DLL or
CTL3D32.DLL, since there are discrete versions of those .DLLs for 95/98/Me and
NT/2K. Your safest bet is to install apps in separate partitions, although a few
programs can be coaxed into running without being reinstalled.

Another thing to be aware of when adding a new partition to a
Windows 9x machine is how Windows 9x translates partitions as drives. In some
cases, if you add a partition, you may break your drive-lettering scheme and
possibly render your Windows 9xsystem unbootable.

Here's an example of this: On a computer that had two primary
partitions, C: and D:, I had Windows NT on C: (which was marked as bootable) and
Windows 98 on D:. When I added a third, logical partition, the drive lettering
was thrown off and D: turned into E:, making Windows 98
unbootable.

There are two simple ways to defeat this. One is to use only
primary partitions (a maximum of four per hard drive) and to add them in
sequence. Another is to add Windows 9x last whenever you set up a system, to
preserve the integrity of the drive mapping. The downside of this method is that
it goes against the common wisdom of putting 95/98/Me on a system first, so this
is recommended with some reservations. Forcing Win9x to map drives a certain way
is difficult and not always successful. (Windows NT and 2000 let you map drives
any way you like and are not as prone to this
problem.)

Third-party Programs for Multiple
Booting

Sometimes the easiest thing to do in
multiple boot scenarios is to let someone else take control of the whole
process. The Windows NT/2K multiple boot loader is not simple to configure and
has no easy way to add operating systems that aren't directly supported. If
you're booting between more than one OS, or various revisions of OSes, the boot
loaders you have may not be enough to do the job.

Boot loaders work in a couple of different ways. Some of them
are installed in a special partition, only a few megabytes in size that is
marked as bootable. When that partition is booted, the boot loader program takes
over and presents the user with a menu of possible boot choices. Usually the
program analyzes the available partitions at each boot, to determine whether
anything has changed since the last boot.

(click for expanded view)
System Commander works with just about any PC-based operating system to let you choose the OS you want to boot.

The best third-party boot loader out there so far appears to be System Commander from Vcom. System Commander automatically detects
any changes made to your PC since the last boot and updates its menus
automatically to reflect those changes.

The makers PartitionMagic also have a multiple boot manager
program named BootMagic, which does many of the same things as System
Commander and supports Windows 2000 as well.

VMware is
another way to run multiple OSes on the same system, but without using multiple
booting. Instead, VMware creates a virtual computer console on your PC
-- basically, a computer within a computer. The virtual computer
runs at about two-thirds the speed of your real computer and has access to many
of the same resources -- disk drives, printers, network, etc. This
allows you to run one or more operating systems, as many as you can devote disk
space for, without having to reformat a drive partition or play around with
dualboot settings.

	(click for expanded view)
	VMware lets you run a 'virtual computer' in your computer, letting you install any operating system you choose. But it'll only work in NT or Windows 2000 and needs plenty of memory.

One
main weakness of VMware is it runs only under Windows NT or Windows 2000, and it
won't work in Windows 95, 98, or Me. VMware also needs a lot of memory and
processing power to get good results: On anything less than a Pentium II 400, it
crawls, and it needs at least 128MB of RAM to really work well. You can try
before you buy, though; the official site contains instructions on obtaining a
30-day trial license via e-mail