Multi-Booting Vista32 and Vista64 WITHOUT Having The C and D Drives Switch Roles


Checked for other messages covering Dual-Boot or Triple-Boot of different Vista OSs, but couldn't find one that covered exactly my requirement.

So here's my question: If I want to add a Vista x64 install to my two existing Vista x86 installs, how do I get the Vista x64 install to NOT use C: as its boot drive letter when I'm booted into it?

I have enough large hard drives already on the machine for each OS to have a dedicated drive for each install and the two existing Vista x86 installs (one is "C" and the other is "F") work fine. In other words, when I boot into Vista install #2 on "F", it boots up as "F" with its Windows folder on F.

I now want to add a third install, but this time it's a Vista x64 OS and when I did this (yes, I already tried) and then booted into this new x64 install, it became "C" (even though it is on the correct physical hard drive I wanted it to be on -- "D") and the previous boot drive (which was "C") is now shown in Disk manager and Windows Explorer as the "D" drive.

Thanks in advance for any assistance.

If you install Vista 64 from within the Vista 86 install you have that considers itself C: than it should prevent C: from being used. In this case, it'll take the next available drive letter or use the letter for whichever partition it is installed to if the partition has already been assigned one.
Thanks for the info.

I believe I tried to install x64 (run the x64 install CD) while I was booted into x86 on the C: drive and it didn't allow me to do that. So I did a clean install of x64 on my D drive, but then wound up with C being D and vice versa.

Is there a way to simply make C (x86) boot and operate as "C" with a C:\Windows folder and D (x64) boot and operate as "D" with a D:\Windows folder?

I've invested a lot of time and would not like to start over from scratch.
The first disk/partition usually gets C:. Some others here have a little bit more experience in terms of getting thier installations set up with the drive letters so they are more consistent. Don't know how many drives you got in the system or how everything is setup, so go from there. My laptop is XP/Vista and Vista always sees itself as C: as well though XP considers it as D:, so unfortunanly I don't think there is much you can do with it after the OSes have been installed.
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There is a MS registry zap to change the system disk letter, but it's designed for situations where the existing OS has been accidentally reset, breaking the system.
Using it in your case, where setup has assigned the letter would probably produce the broken system it's designed to fix.
The relevant gen from Vista help on disk letters assigned at setup is pasted in this post, but you've run into the problem of not being able to run the 64bit setup from a 32 bit system, limiting your options.
If you'd been installing 32bit after 64 you'd have got what you wanted.
My XP boots as D, calling Vista C, and Vista boots as C, calling XP D, which is the way I want it.
But it doesn't have to be that way. A lot of people like their booted system always to be C.
In some ways that's preferable because a lot of stupid 3rd party software (like most Adobe programs) will put some stuff on C: even when you install it on D (if it can see a C: to put stuff on), which can cause unpredictable behaviour when the same software is also installed on C.
In my case it doesn't happen because Vista is hidden from XP so it can't find a C disk to b*gger around with.
You might like to consider the consequences of having a visible C: disk which isn't the booted system.
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