the only problem I've even encountered while doing this is that the sequentially assigned drive letters often occupy
the letter I want to use for a specific task, so you need to be prepared to assign a "temporary" drive letter to some volumes to free up the letter you want to use.
but the one iron clad rule is that C (your system) drive (or partition on a drive) must remain C
Personally I prefer my primary optical drive to be "D" and XP/Vista/7 often uses that letter somewhere else, so I've gotta change things around to "free up" the desired letters.
I run my system as a "Tri-Boot", I have XP-Pro, Vista Ultimate & Win7 Ultimate available.
But I have those OS's are all on seperate physical drives, which are installed in removeable
drive drawers so only the active drive (or one of it's redundant clones) is even physically
installed in the computer.
THE aggrevating thing is that my pair of 750gb data drives are formatted as "dynamic" (simple) volumes
And each time I switch to a different OS the just booted OS sees those drives as "foreign" volumes which must be "imported", It's only a few mouse clicks to correct it but it is annoying to need to...
Each and every time... (Kinda like the lack of a Desktop icon in the taskbar in Win7)