BSOD during OS install

Hi all, new to posting but I've been helped out many many times by this forum. Anyways, I've been having problems with BSOD's (mostly system_service_exception) on my brother's PC and after cleaning up several viruses/spyware and failing a system restore and windows repair it ultimately came down to me doing a fresh OS install. I am trying to install Windows 7 Ulitmate 64 (same exact OS it previously had) but each time I am getting a BSOD with IRQL_NOT_LESS_OR_EQUAL. I have taken his HDD and formatted it with my PC and still get the same problem. I built his PC about a year ago and had to deal with BSOD's only when he played games (which was solved by manually setting the memory timings in BIOS) with no further problems until now. Here is a list of his components:

Motherboard: XFX 750i SLI 775 DDR2

CPU: Intel Core 2 Duo E7500

PSU: Apevia 1100W Warlock Power

Memory: Corsair XMS2 2048MB DDR2

Video Card: BFG GeForce GTS 250 1GB GDDR3

HDD: Seagate Barracuda 7200 500GB

If you need any more info please let me know and I'll post what I can, but the HDD has been formatted so I'm not sure what else I can offer. Thanks in advance for any help and advice!