We reported about an possible driver bug in 2xFSAA mode earlier. It turned out that this is not drive bug but rather a limitation of the R200 GPU which renders in a fixed FSAA mode if fog is enabled. ATI's Jeff Royle cleared that up... Read more for his statement... I talked to the driver people and they say this is a known limitation actually. When fog is enabled a fixed pattern is used for the AA, future parts may not have this limitation. Max Payne can be explained with this as well it seems. Some of the other games which you mentioned don't have AA on the vertical edges, this may be because of the fact they could lie on the edge of an AA pixel grid and so it doesn't blend in all cases. Regards,
Jeff Royle