I plan to set up a partition on my main "C" HDD using GParted & install Windows 7 beta so I can dual boot Windows 7 & XP. I happen to have a 2nd "D" HDD on my computer. If I instead install Windows 7 on the 2nd "D" HDD, will I be able to then dual boot with XP on "C" and Windows 7 on "D", or is it necessary for all operating systems be on the same HDD in order to be presented with the dual boot option at bootup?
Either way should work fine, just be sure to watch for the custom setup option so you can point the setup to the correct partition or drive. Rule of thumb with dual booting MS operating systems is install oldest first.
A good backup of important files is always prudent as well.