To the guys saying it's an on/off switch - no it isn't.
AntiAliasingLevel is just that, the level of anti-aliasing.
I know this, as well as many others, who've also had to edit their ini files.
I've tested mine on 2x, 4x and 8x and there is a noticable difference between all three settings.
To the poster who said I was ignorant, it's the other way around I'm afraid.
But hey, don't take my word for it, test it for yourself. Probably a good idea before making comments based on assumptions and guesswork.