Hey...
Almost all of the games that i play crash sometimes and then recover again.
Sometimes it ends up with BSOD. For Example, Crysis, Flight Simulator X, Prototype, CSS, World Of Warcraft work fine.. no crashes or anything but Fuel - Crash/BSOD, Cod4 - Crash, Call Of Yuarez: Bound In Blood - Crash/BSoD, Riddick: Assault On Dark Athena - Constant Crashes and BSOD (UNPLAYABLE) and that list can go on forever i guess.
PC Specs:
Intel Core 2 Duo E4500 @ 2.20GHz
3GB RAM (1x 2GB, 1x 1GB)
Club3d HD4850 512mb Overclocked Edition (Latest drivers)
580W PSU
Windows Vista Home Basic 32-bit Service Pack 2
RAM - tested, No errors with over 700% coverage
Scanned whole PC With AVG Free. It found a bunch of cookies but i successfully deleted them

Scanned with spybod S&d - Clean
NO overheating problems.
I have heard some people update their PC bios... what's that and how is it good? I have never done that.
Ask me if you need more information.
EDIT: Oh and the PC is 2-3 years old. I have upgraded RAM (originally 2x1GB, PSU (Originally a crappy 400w PSU) and GPU (Originally POV 8600GT 512mb) . And please don't tell me i need to buy something new. Let's not make this thread a shopping mall.