I had this weird problem where it looked like I if my AA and AF would'nt kick in.
Sometimes my graphics looked great and in some other places it looked like crap. I was running this on 1680 x 1050. I've changed that to 1470 x 917 (22").
My game now looks great and plays great. Don't know what kind of FPS I have but if feels really smooth.
But...I find it pretty weird to be honest.