Hi, Jim.

This is why I always use Disk Management to give my volumes names, in
addition to the "drive" letters. The letters are only temporary and get
reassigned from time to time, but the names are written to the hard drive
and will be the same, no matter which Windows version is running. So the
first partition on my first HD may be C: when WinXP is running and D: when
I'm booted into Vista, but it will always be "SATA 120". And the second
partition on the second HD will always be "Vista x64", which Vista calls C:,
even when I'm running WinXP, which might call it Drive V:.

As I'm sure you know, "drive" letters are not assigned to hard drives, but
to volumes (primary partitions and logical drives) on the physical disks.
And "drive" letters also are assigned to CD/DVD drives, network drives, USB
flash drives, digital cameras and card readers - and probably other devices
that I don't know about - and these also can change as we add or remove
devices.

The terms "system partition" and "boot volume" are used counterintuitively:
we boot from the system partition and keep the operating system files in the
boot volume. Each computer will have just a single system partition, even
in a dual-boot system, and will have a separate boot volume for each Windows
installation. See this KB article:
Definitions for system volume and boot volume
[url]http://support.microsoft.com/kb/314470/EN-US/[/url]

This concept is at the heart of dual-booting. First, we install WinXP; its
Setup assigns letter C: to the System Partition and, if we choose a
different volume for WinXP, that volume will become D:, even if it is on a
second HD. Then, if we like, we can create other volumes and assign letters
to them, using Disk Management. If we then run Vista Setup from the WinXP
desktop, Setup will see those letters and use them.; if we create a Drive V:
in WinXP and tell Vista Setup to install Vista there, then Vista's boot
volume will be Drive V: in both WinXP and Vista. And both systems will see
the System Partition as Drive C:.

But if we boot from the Vista DVD to install Vista, its Setup has no idea
what letters WinXP has assigned, so it uses its own algorithm, which assigns
C: to its own boot volume, no matter which HD that might be on, and then
assigns the next letter (D:) to the System Partition, if it is a different
partition from the boot volume. So it's easy to get letters like mine,
where C: is the boot volume in Vista (2nd volume on 2nd HD), but the System
Partition in WinXP (1st partition on 1st HD). The System Partition is C: in
WinXP and D: in Vista. That might confuse us humans, but it doesn't bother
either Vista or WinXP. After working with it for a while, it doesn't bother
me, either, since I've learned to rely on the volume names, not letters.

As you suspected, we can't easily change the letters for the System
Partition or the Boot Volume except by running Setup again, which means
re-installing the operating system. All the other letters can be changed by
running Disk Management - in each OS.

If WinXP is installed first, Vista's Setup will detect it and create the
dual-boot arrangement automatically. On reboot, the operating system menu
will offer to boot Vista or the "Earlier version of Windows". If we choose
Vista, the boot continues as though WinXP did not exist. If we choose
"Earlier...", Vista will step out of the way and use NTLDR and NTDETECT.COM
to present the familiar Boot.ini menu, just as though Vista didn't exist.
In either case, the boot process will start in the System Partition and then
branch to whichever boot volume we choose.

RC
--
R. C. White, CPA
San Marcos, TX
[email]rc@grandecom.net[/email]
Microsoft Windows MVP
(Running Windows Live Mail 2008 in Vista Ultimate x64 SP1)

"jim" <jmlvy********.com> wrote in message
news:C0EB876A-28AD-439E-BC57-8FAC1BA0CFC3@microsoft.com...[color=blue]
> Why when I boot into windows xppro does it recognize the partition it is
> installed on as D: and when I boot to Vista Home Basic and see the same
> partition that XPPro is on it is F: ? I want to dual boot the two
> operating systems? Un able to change drive letter to D: in windows vista
> home basic? Believe this is reason I can't boot both systems. I can get to
> windows xppro if I use install cd and go to recovery and fix boot. After I
> reboot to vista home basic dvd and do repair startup. reboot and get
> options for both operating systems. Go into vista alright. Reboot and
> select xppro and gest something about ntldr missing. Tried copying ntldr
> and ntdetect.com via xppro cd and recovery console to drive D; wich xppro
> reconized. Still vista home basic recognizes xppro on F: and not D:? Any
> help as to how I can change partition drive letter in vista to D: or how I
> can get them(op systems) to both boot without clean install? Maybe I just
> think I know what is wrong? Any help would be great! Thanks in advance.
> Installed Vista from image to c: drive and used shrink drive frome disk
> manager to create partition or unallocated space then from an ghost image
> file installed xppro on the unallocated part of the drive? Help is needed![/color]