Random BSOD'ing and games crashing

Specs: Intel Core 2 Duo E6850 3.0 Ghz
N650SLI-DS4 Motherboard
evga e-GeForce 8800GTS
2 GigsCorsair DDR2 800MHz Ram-currently 1 gig
500GB Seagate Barracuda
18X LG DVD burner
OCZ 700 Watt PSU
X-Blade Gaming Case
Windows Home SP2

Problem: My computer Blue Screens when I've been playing any of the games I've gotten installed. I can always re-create it in Supreme Commander after a half hour of playing. It doesn't always blue screen though, sometimes it just crashes and the "This application has suffered and error and must close any unsaved information will be lost" sometimes with the option to send an error report to Microsoft.

I built this computer... 1 week ago, and it's been doing it since I built it. I've tried a couple of things, such as reseating everything, adding more cooling. I ran memtest and it shot back a few errors on one stick of ram, so I took it out, and bioshock ran fine for 3 hours last night/this morning. I went back to play it today though, and it went back to crashing every half hour. I've also tried updating the drivers on everything, and used three different drivers for my video card: The ones that came with it, the latest non-beta on nvidia's page 162.18, and the beta drivers 163.44 and I've gotten blue screens with them all. I tried the different drivers because before I took out my one stick of ram, I was getting nv_disp.dll blue screens.

In fact, it actually just blue screened on me, and the error I got was a IRQL NOT LESS OR EQUAL when I was playing Supreme Commander.

I included the files window's creates on a blue screen in the zip file I attached.

So.. if you can help me and can hack your way through my rambling, any help you can give me to fix this problem would be great

 

Heres some info,

http://pressf1.pcworld.co.nz/showthread.php?t=53947