I, on the other hand, am driven crazy by no AA. Just 2 or preferably 4x is plenty for me though. I just messed around with CoD4 and put it on 32x AA 16xAF....was getting about 24fps average @ 1680x1050 max details! I was quite surprised it did that well.....
Anyway....if you want to go crossfire then get a X38 board like the P5E, QuadGT, any of the dfi boards....
9600GTs in SLI are amazing performance for the money, and you could get an older 680i board for cheap....