Occasional freezing when playing video/sound

Hey guys, i am having a problem with what seems to be what I think is a driver problem, but i could be wrong. My woes begun awhile ago on my custom build computer playing certain games with the sound on. It would freeze for about 7-10 minutes, then go back to it's normal state, playable until a unknown duration thereafter until it did it again. I started getting this problem about a year ago, when i had vista. I recently got the windows 7 64 bit RC version and put that on. Im using a 9800 gtx + for my gpu, and a sb x-fi sound card. I have ran every test under the sun, stability tests, (nothing is OCd), anti-virus, spyware, registry, memtest, prime95, hard drive tests, and iv'e done the ritualistic task of checking all of my drivers frequently. As far as cooling goes, speedfan indicates that everything is running fine, and ventilation is no problem for my case. Any ideas would be appreciated

Case: Antec 900
Power Supply: KINGWIN Mach 1 ABT-700MA1S 700W ATX
Motherboard: Asus p5E
CPU: Intel Core 2 Quad Q9550
Ram: G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) and some 2gb fillers for the rest
Hard drive: Seagate Barracuda ST31500341AS 1.5TB
Video Card: EVGA 512-P3-N874-AR GeForce 9800 GTX+
Sound Card: Creative X-FI XtremeGamer
OS:Win7