Graphical glitch

Hi all

When playing games with alot of textures I get a thin layer of static over the 3D rendered areas. Note that it does not appear over 2D areas like hotbars and menus and such. Also, games that don't use tons of "next gen" effects (like WOW) don't seem to be affected as much. Here is my setup:

Asus A8n-SLI deluxe
2.4 gig amd 64 (not dual core)
2 Gigs Ram
Gforce 7800 GT

At first I was thinking maybe there wasn't enough juice getting to my graphics card since I only have a 500W psu. Now, I'm not so sure thats the problem. Here is a screenshot from one of my games to show you what I'm talking about.
http://img370.imageshack.us/img370/448/screenshot00003jy4.jpg

edit: Also, I dont think it's the drivers since I've tried at least 3 different sets including the most recent ones.