What does anti-aliasing do?
Anti-Aliasing “smooths” the square junctions. Most objects are drawn digitally for video rendering. This makes objects appear very rough around the edges. Anti-Aliasing and Anisotropic filtering make objects appear more smooth and life like. If you run 16X AA you’ll slow the game to a snails pace with that video card. Think 10 frames per second or less. With the card you have and the game you are talking about I would suggest you leave it at 2XAA max. If your frame rate is dragging turn AA off. If you want to run it at 16X AA you need more powerful hardware. Dual 4870s or a GTX 280 video card might give you a decent frame rate at 16X AA, depends what resolution you play at also. I typically run my QX9850 with Dual 8800GTs at 4XAA, but I use 1680X1050 res on this 22″ LCD too.