Help, BSOD after SP2 install, can't roll back??

Installed Vista SP2. I reboot, I get a BSOD with IRQ not less or equal. rest of the error just said STOP with a bunch of 0's and 1's - no drivers listed. Looked up advice, booted into safe mode, cleaned up drivers, etc.

Rebooted, now a BSOD with "tried to execute memory in non executable memory" or something like that.... screw it, I put in repair CD. Cannot repair boot automatically. Need to use system restore.

I've tried restoring twice which works... sort of. Now I can boot into normal mode with no BSOD, but as soon as it finishes I can't login in, it goes straight to installing SP2.... stage 1 of 3 --% complete screen. If i let it finish, same problems again.

I don't care about SP2 anymore. I JUST WANT TO BOOT WINDOWS!! Ahh. So annoyed.

Is there anyway around this? Is there a way to cancel the stupid SP2 install so my system just works again? Even trying to boot into safe mode it just launches the SP2 install!!