Hi, David.
You've received plenty of good advice here. You don't really need more,
but... ;^}
Ever since WinNT4 (which is where I jumped in to dual-booting), the
Microsoft dual-boot (actually multi-boot) system has consisted of two parts:
The System Partition and the Boot Volume. For the official but
counterintuitive definitions of these two terms, see KB 314470 (
http://support.microsoft.com/kb/314470/EN-US/ ). As others have said, those
uninformed on such matters may think it strange that we boot from the system
partition and keep the operating system files in the boot volume - but those
terms are rooted in computer history and we're stuck with them. I see this
as a figure "Y". It all stands on the upright portion, the System
Partition. The boot process starts there, then proceeds to one of the two
(or more) branches of the "Y", depending on what we select. (In a one-OS
system, the "Y" looks like an "I", but the System Partition and Boot Volume
still exist - and the distinction is still important.)
The System Partition must be a primary partition and marked Active
(bootable), and it must be on the HDD designated in the BIOS as the boot
device. The Boot Volume may be a primary partition, but it also may be a
logical drive in an extended partition on any HDD in the computer. If there
are multiple Windows installations, each will have its own Boot Volume, but
they will all share the single System Partition. (More complex arrangements
are possible, such as creating a System Partition on each of multiple HDDs
and changing BIOS settings to choose between them, as some have suggested in
this thread, but let's keep it simple for the current discussion.)
The System Partition can be very small (well under 1 GB) because all that is
required to be there are the boot sector (512 bytes) and the few relatively
small startup files. The Win2K/XP startup files are only NTLDR,
NTDETECT.COM and Boot.ini. For Vista/Win7, they are only the file "bootmgr"
(no extension) and the folder named \Boot, which holds the BCD (Boot
Configuration Data). No matter where you tell Setup to install Windows,
these startup files MUST be in the System Partition.
All the rest of Windows (maybe 10 GB or more for Vista) will be installed in
a single folder tree, named \Windows, in the Root of whichever volume you
choose, which thereby becomes the Boot Volume for that Windows installation.
This CAN share the System Partition - and that is the typical arrangement,
especially for newbies and for new computers with Windows pre-installed.
But this means that you can't format that Boot Volume without also wiping
out the System Partition. (Win7's default installation on a new blank
computer solves this by creating the System Partition as a separate volume
with no drive letter, then creating the large boot volume and assigning it
Drive C:. But that arrangement is not available to us when adding Win7 to
an existing WinXP system.)
WinXP's Setup.exe never heard of Vista or Win7, of course, because those did
not exist back in 2001, when WinXP was released. But Vista and Win7 Setup
knows how to handle an existing WinXP. That's the reason for the Golden
Rule of Dual-Booting: Always install the newest Windows last. When Win7
Setup finds an existing WinXP, it does not delete NTLDR, etc., but adds its
own bootmgr and \Boot folder alongside them, then rewrites the boot sector
(after saving a copy of it). Later, on each reboot, the BCD menu includes
an option for an "Earlier version of Windows". If you choose that, the BCD
gets out of the way and lets NTLDR present the familiar Boot.ini menu - if
there are multiple Win2K/XP options - or continues directly into WinXP if
there is only one. Since you want to add WinXP to a system that already has
Vista installed, you'll need to do some repair work after installing WinXP,
but that's easier than it used to be. And upgrading from Vista to Win7
later should be easy, although Microsoft hasn't yet published the details of
this transition.
Well, that's enough for now. We could discuss drive letters and such, or
creating multiple System Partitions on your multiple HDDs (for insurance in
case one HDD gets damaged), but we can save those for another day.
RC
--
R. C. White, CPA
San Marcos, TX
(e-mail address removed)
Microsoft Windows MVP
Windows Live Mail 2009 (14.0.8064.0206) in Win7 Ultimate x64 RC 7100
