Geez, how are you getting decent framerates? I've got a 7600GT, 2GB RAM, and a C2D, think it's an E6600, 2.4GHz processor. I've turned it down to 1440x900, 2xFSAA, lowest possible settings for textures, model quality, shadows, and shader quality, reflections low, etc etc, and it still drops down to 20fps on outdoor levels, especially when trees are around.
Running at 1680x1050 turned into a slideshow when all the Striders started running around.
Are you guys on Vista with DX10?
WinXP + DX9.something here. I will install Vista the day a Microsoft rep threatens to shoot me unless I install it.