I run 2 1680x1050 monitors with 5 clients total: 4 at minimum settings on the left and one and full screen max settings on the right.

I use the 8800gtx with 768meg and have a Q9450 cpu.

With the 4 low res clients limited to 20 fps, I get 40-50 fps from the main out in the world and at least 20 in town.