Well, it's \_possible_ but you'd essentially have to dual/multi-boot with completely separate OS installs.
The way I'm doing it:
fdisk -l /dev/sda
Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 5 40131 83 Linux
/dev/sda2 * 6 2438 19543072+ 7 HPFS/NTFS
/dev/sda3 2439 8831 51351772+ 5 Extended
/dev/sda5 2439 2563 1004031 82 Linux swap / Solaris
/dev/sda6 2564 3435 7004308+ 83 Linux
/dev/sda7 3436 4058 5004216 83 Linux
/dev/sda8 4059 7098 24418768+ b W95 FAT32
/dev/sda9 7099 8096 8016403+ b W95 FAT32
/dev/sda10 8097 8831 5903856 83 Linux
( you can do without /dev/sda1; separate /boot is pretty well deprecated now )
/dev/sda2 = Win XP with Vmware Player
/dev/sda5 = Shared Swap between Linux OS's
/dev/sda6 = /home
/dev/sda7 = 64-bit Ubuntu Linux 6.06 LTS with Workstation 5.x (main environment)
/dev/sda8-9 = FAT32 drives for cross-OS data sharing
/dev/sda10 = 32-bit Ubuntu Linux 6.06 LTS with Server
/mnt/vmware is on a completely separate drive, and I also keep the Workstation VMs separate from the Server ones.
--Personally I find the 64-bit Ubuntu to be subjectively "faster" than the 32-bit on the exact same hardware; YMMV.
ls -al /boot == (edited) From the 64-bit side, which was installed after XP... I use symlinks so don't have to change the 1st entry in Grub; the 32-bit install gets its own kernel from its /boot dir on sda10:
-rw-rr abi-2.6.15-26-amd64-generic
-rw-rr config-2.6.15-26-amd64-generic
drwxr-xr-x grub
lrwxrwxrwx initrd.img -> initrd.img-2.6.15-26-amd64-generic
-rw-rr initrd.img-2.6.15-26-amd64-generic
drwx------ lost+found
-rw-rr memtest86+.bin
lrwxrwxrwx System.map -> System.map-2.6.15-26-amd64-generic
-rw-rr System.map-2.6.15-26-amd64-generic
lrwxrwxrwx 2006-08-28 20:22 vmlinuz -> vmlinuz-2.6.15-26-amd64-generic
-rw-rr vmlinuz-2.6.15-26-amd64-generic
=== BEGIN Example /boot/grub/menu.lst
\# menu.lst - See: grub(8), info grub, update-grub(8)
\# grub-install(8), grub-floppy(8),
\# grub-md5-crypt, /usr/share/doc/grub
\# and /usr/share/doc/grub-doc/.
\## default num
\# Set the default entry to the entry number NUM. Numbering starts from 0, and
\# the entry number 0 is the default if the command is not used.
#
\# You can specify 'saved' instead of a number. In this case, the default entry
\# is the entry saved with the command 'savedefault'.
\# WARNING: If you are using dmraid do not change this entry to 'saved' or your
\# array will desync and will not let you boot your system.
\# WIN XP
#default 1
default 0
\# Linux
\## timeout sec
\# Set a timeout, in SEC seconds, before automatically booting the default entry
\# (normally the first entry defined).
timeout 5
\## hiddenmenu
\# Hides the menu by default (press ESC to see the menu)
#hiddenmenu
\# Pretty colours
#color cyan/blue white/blue
#
\# examples
#
\# title Windows 95/98/NT/2000
\# root (hd0,0)
\# makeactive
\# chainloader +1
#
\# title Linux
\# root (hd0,1)
\# kernel /vmlinuz root=/dev/hda2 ro
#
#
\# Put static boot stanzas before and/or after AUTOMAGIC KERNEL LIST
\# 0
title Ubuntu, kernel 2.6-amd64 SMP
root (hd0,6)
kernel /boot/vmlinuz root=/dev/sda7 ro vga=ext
initrd /boot/initrd.img
savedefault
boot
\# 1
title Win XP Pro
root (hd0,1)
savedefault
makeactive
chainloader +1
\# 2
title Debian Testing SDA10 32-bit SMP
root (hd0,9)
##chainloader +1
kernel /boot/vmlinuz root=/dev/sda10 ro vga=ext
initrd /boot/initrd.img
#savedefault
boot
\### BEGIN AUTOMAGIC KERNELS LIST
\## lines between the AUTOMAGIC KERNELS LIST markers will be modified
\## by the debian update-grub script except for the default options below
\## DO NOT UNCOMMENT THEM, Just edit them to your needs
\## ## Start Default Options ##
\## default kernel options
\## default kernel options for automagic boot options
\## If you want special options for specific kernels use kopt_x_y_z
\## where x.y.z is kernel version. Minor versions can be omitted.
\## e.g. kopt=root=/dev/hda1 ro
\## kopt_2_6_8=root=/dev/hdc1 ro
\## kopt_2_6_8_2_686=root=/dev/hdc2 ro
\# kopt=root=/dev/sda7 ro
\## default grub root device
\## e.g. groot=(hd0,0)
\# groot=(hd0,6)
\## should update-grub create alternative automagic boot options
\## e.g. alternative=true
\## alternative=false
\# alternative=true
\## should update-grub lock alternative automagic boot options
\## e.g. lockalternative=true
\## lockalternative=false
\# lockalternative=false
\## additional options to use with the default boot option, but not with the
\## alternatives
\## e.g. defoptions=vga=791 resume=/dev/hda5
\# defoptions=vga=ext
\## altoption boot targets option
\## multiple altoptions lines are allowed
\## e.g. altoptions=(extra menu suffix) extra boot options
\## altoptions=(recovery mode) single
\# altoptions=(recovery mode) single
\## controls how many kernels should be put into the menu.lst
\## only counts the first occurence of a kernel, not the
\## alternative kernel options
\## e.g. howmany=all
\## howmany=7
\# howmany=all
\## should update-grub create memtest86 boot option
\## e.g. memtest86=true
\## memtest86=false
\# memtest86=true
\## should update-grub adjust the value of the default booted system
\## can be true or false
\# updatedefaultentry=false
\## ## End Default Options ##
title Ubuntu, kernel 2.6.15-26-amd64-generic Default
root (hd0,6)
kernel /boot/vmlinuz root=/dev/sda7 ro vga=ext
initrd /boot/initrd.img
savedefault
boot
title Ubuntu, kernel 2.6.15-26-amd64-generic Default (recovery mode)
root (hd0,6)
kernel /boot/vmlinuz root=/dev/sda7 ro single
initrd /boot/initrd.img
boot
title Ubuntu, kernel 2.6.15-26-amd64-generic
root (hd0,6)
kernel /boot/vmlinuz-2.6.15-26-amd64-generic root=/dev/sda7 ro vga=ext
initrd /boot/initrd.img-2.6.15-26-amd64-generic
savedefault
boot
title Ubuntu, kernel 2.6.15-26-amd64-generic (recovery mode)
root (hd0,6)
kernel /boot/vmlinuz-2.6.15-26-amd64-generic root=/dev/sda7 ro single
initrd /boot/initrd.img-2.6.15-26-amd64-generic
boot
title Ubuntu, memtest86+
root (hd0,6)
kernel /boot/memtest86+.bin
boot
\### END DEBIAN AUTOMAGIC KERNELS LIST
\# This is a divider, added to separate the menu items below from the Debian
\# ones.
\# This entry automatically added by the Debian installer for a non-linux OS
\# on /dev/sda2
./. If you have appreciated my response, please remember to apply Helpful/Correct points. TIA
