I usually run at 1280x1024, the most AA I can usually get away with without any slowdown is 2X, and often not even that.
BTW, BF2 doesn't need 2GB of ram to run smoothly, just more than 1GB. Of course, if you want to run in dual channel, you more or less need 2GB then.(I guess 1.5GB could work, 512+256 in each channel)