Windows 7 x64 Professional Freezes

Hi all, i hope you can help me

I built a new pc yesterday, and ever since i built it, i have had problems with windows 7 freezing randomly. Originally i noticed the cpu temperature was way too high (70 degrees!) so i replaced the thermal grease, and now it is back to around 50. however, windows still continues to freeze at random intervals.

my specs:

windows 7 x64 professional (clean install)
samsung spinpoint 320gb hdd sata (operating system is on here)
hitachi deskstar 500gb hdd sata (storage/games)
2x2gb OCZ pc2-6400
asus p5n-D motherboard ( "apparently" windows 7 compatible xD)
intel quad core q8400
Point Of View GTX 275 Joker Edition

all drivers are windows installed apart from graphics, using microsoft security essentials, and any help would be greatly appreciated.

Ryan

When does it freeze? I have windows 7 64 bit on a home grown computer also and experince a freeze once the pc is left idle for along period. It isnt consistent in that some of the time I can shake the mouse and after a short nonresponse period the os kicks in. Is that similar to your situation?