Hopefully that will help you narrow things down to at least a hardware or a software issue.
test your hardware
Well guys. I'm pretty sure its my hardware. Recently, I upgraded to Win7 64 bit and 8GB DDR2 1066 Kingston HyperX, http://www.valueram.com/datasheets/KHX8500D2T1K2_4G.pdf , but its only programmed for 800. That's okay cause I just went to the BIOS and changed my crap according to the data sheet. Worked great for a couple weeks then about 5 random BSOD's before I Memtest. Sure enough there were 16 errors withing 3 hours. I've since reduced my RAM to the 800MHz and went back to auto for everything else. Been running prime95 all night and still moving right along. If anyone wants to look at the BIOS settings I see, check my ImgShack HERE and feel free to recommend something to try. I'm still tweaking on it myself.
Windows7 64 bit
600W OCZ Mod Stream Pro
The errors might have been caused by low voltage settings for the RAM
When you start working with 4 sticks of RAM you often need to step up the voltage a bit.
What voltage were you using when running @ 1066Mhz? The data sheet suggests 2.2-2.3V. Even @ 800Mhz and 4 sticks of RAM I'd think 1.9-2.0V could help stability.
The performance difference between 800Mhz and 1066Mhz is really very small. A slight nudge up in CPU speed would be a better overall performance improvement.