I agree in that the lack of AA in some titles is unnoticeable, while in others it's horrible. In Far Cry, the jaggies are just brutal, so I must have it on. In older games aliasing gets fairly bad too. However, even just 2xAA wipes out most of the jaggies fairly well. I only max AA if I can afford the performance hit. AF I usually try have 4x of at least, as it really does look much nicer.