Graphics distortions -- please help!

Hello, I've recently bought a new system. Here are the specs:

e6750 2.66 ghz
8800 gtx
2 gb ram

Nothing is overclocked, except the ram. But that was done to get it to the suggested settings, as it came underclocked. I have the latest drivers installed. The problem is that in almost every game I play when I move around there are these distortions in the graphics, like these lines appear or something. I'm having a hard time explaining it, so if you look at this video while I'm playing Portal you can see. Does anybody know what the problem could be?

http://www.personal.psu.edu/byk501 [...] rtions.AVI

Thanks

thank you! that was it, i can not believe it was something so simple.