BioShock 2 for PC Graphics?

I bought BioShock 2 on my PC after having played the original extensively (It's a great game), and so is this one. Except for the fact the the stupid graphics are terrible and i can't do anything about it (too my knowledge). By this I mean, the ant-aliasing is just... so bad. The weird thing is, Multiplayer and the original run and play better. I was thinking myself that it could be because I don't have DX10 high details turned on, but I have XP and it would super cheap of microsoft and 2K to make it so that you NEED DX10 for singleplayer to look good. My system specs are: Nvidia GeForce 8800 GTX, 1gb RAM, and some sort of really good processor that holds up my system, but most games run properly because it's a gaming specific computer, and is custom built. If you think upgrading the RAM would help (I want to anyways, 1gb isn't enough) or have any other suggestions, please tell me. Also, I just upgraded the Nvidia drivers, so that can't be it.