Gamer1, get a Radeon9700 or a 9500PRO instead. They handle AA and AF like cake compared to the GF4's. Prices should drop by then. (especially the 9500PRO which is cheaper than the 4600 yet performs better when AA and AF is on)
iD said that D3 would require but only 1Ghz of CPU speed, while the video card is most burdened. But I dont know how close their statement may be to the full complete version of the game. You have to remember that the alpha version is probably not optimised at all, too.
Nightwolf: I have no idea what are you talking about.