I think this can be done, but its not real easy.  The problem is that you
may have shortcuts on your system that now point to drive D that you want to
point to you the C drive after you make it C.

So:
1. disconnect all drives except the drive you want to be C: and reformat it
(you will lose everything, so back up what you want first).  Install Vista.
2. plug in the drive you want to be D: and reboot, verifying that it is seen
as D: in Vista.  Make sure that the boot order in the BIOS has the C: drive
having priority over the D: drive.
3. Plug in the drive you want to be E: and reboot, verifying that it is seen
as E: in Vista.  Make sure the boot order is C:, D:, E:.
Note that any shortcuts on D: or E: that previously pointed to a different
physical drive need to be fixed too.
Note too that Boot.ini types of files my now point to different drives than
they had previously too.

-Paul Randall