I have a similar situation in mind but I want to do something different. I have a dual boot XP / Win 7 x64 system with XP loaded first. I want to have a triple boot config with XP. Win 7, x64 and Win 8 x64. However, XP is on an (older) separate drive. Win 7 is on an 120 gig SSD which I want to keep as my primary drive (with Win 7 and Win 8 OSs). So I would like to:
1) Shrink the SSD C: drive partition (Win 7) to create a new 40 gig partition for Win 8 . I plan to do this with PerfectDisk 11 Pro (I tested it and with some tweaking it appears like it will work).
2) Install a fresh copy of Win 8 x64 on the new partition, in a triple boot XP/Win7/Win 8 configuration for software compatibility testing. Keep the XP OS on the older drive for programs that don't like to play along with Win7.
3) Assuming there aren't any issues with win 7 / Win 8 compatibility, uprgade the existing Win 7 OS to Win 8 to preserve programs, settings etc.
without losing the original Win 7 installation. In other words now it will be a triple boot XP/original Win 7/ Win 8 upgrade from 7. I've already tried the Win 7/8 upgrade on a laptop and it worked just fine, but it doesn't have the software I need to test for compatibility. If I can I'd like to do this overtop of the fresh Win 8 install since I won't be needing it anymore.
I assume I am going to have to do this with some defrag like PerfectDisk, a bootloader pgm, and probably something to image the Win 7 install (I have Acronis backup & Recovery 10). Does that sound about right? Anyway I'm not sure how to do it without blowing some/all of my PC to bits