* PLEASE * help me asap! Vista 32 & boot problem

Quick system rundown:
eVGA 680i A1 with Intel Quad Core Q6600
eVGA 8800 Ultra
Vista 32
Crucial Ballistix PC28500 (DDR26400)

Please help. I have two hard drives. One I had a complete clean (brand new harddrive) install of vista, and after that I hooked up my old hard drive (with xp on it). The old hardrive is a SCSI, and the new one is SATA.

Anyway, old HDD stores my music, and videos, etc.

Long story short, new system runs flawless until I, Mr stupid, try to tweak the system. I guess I'm not happy with the fast computer here.

Three times the computer had a BSOD (blue screen of death), and all three times the memory dumped to hard drive. Third time, however, the computer won't boot past the Windows Vista animation green scrolling thing. It goes to that, then black screen, then PC reboots.

I know this isn't a RAM problem, because when I use other HDD it boots up XP fine (I know this is a no no) but I had to test it.

Future Shop says it is a boot sector problem. What can I do?

Do I have to reinstall Windows Vista?