I have a 27 in, 3.06 C2D iMac with a 4850 video card. Ever since I installed Windows 7 I have this pixelated background issue with every wallpaper I use. The wallpapers are from interfacelift.com and are the correct resolution (I've tried the stock wallpapers as well). I've updated the drivers from ATi, updated bootcamp to 3.1, and I can't for the life of me fix the problem. Ideas?