Windows 7 freezes when I play 3d games

Windows freezes at random interval's while I play game's, but it seems to be only with certain games not particularly graphically intense but 3d accelerated none the less. I've done everything I can think of to fix it,

1)Scan disk
2)Defrag
3)Mem-test
4)Windows totally updated
5)Tried drivers version 185, 190
and 192.62 or whatever the latest ones are from 1/8/10
6)I checked my drives to ensure there was no corruption
7)disabled services
8)disabled programs at startup
9)Scanned my registry
10)Scanned for Malware
11)Scanned for Virus's, spyware all the stuff.
12)turned of the UAC
13)ran in compatiblity mode (which never works so I don't know why I ever bother doing it)
15)all my other drivers are the most recent version even my mouse.
16)tried 2 different Nvidia cards.
17)change all kinds of settings in bios, even the stupid cool'n'quiet bs.
18)questioned myself on why I bought an Nvidia card since my wife has an identical computer with an ATI card and has no problems.
19)Checked the event logs, all thats in them is error auditing has stopped, and the computer is recovered from my un=lawfull attempt to hard-restart it after it froze.
20)I have a 750 Corsair PSU no problem with power,
21)my cpu at max runs at 40C, my GPU is max around 50.
22)I tried all the suggestions Nvidia offered which equals 0
23)I tried all the support microsoft offered which was ensure the power is turned on.
24)dxdiag say's everythings ok.
25)Disabled the Aero Theme
26)Tried Completely disabling my second monitor.
27)Updated motherboard drivers, Chip set drivers,
28)Checked Reliability monitor and Events log, nothing.
29)Disabled physx.

I don't know what to do with it, I meen theres a-lot of stuff I have done other then that I cannot remember even. It ran fine on vista 64, which this computer was on when I upgraded to 7 Ultimate 64.

Anyone have any other suggestions?

AMD Phenom +9650
4 Gig 1066 Ocz Platinum
XFX8200 Motherboard
500 Gig Sata
300 Gig IDE
2 x DVD Sata
Corsair 750W PSU
Onboard Audio
Onboard Network Adapter
Nvidia 9600 GSO
G15 Keyboard
Microsoft Keyboard
X250 or 500 or some crap logitech speakers.
Windows 7 x64 Ultimate.