For best performance you want to use 2 identical cards... and if you are on windows XP get vista 64bit or even xp 64bit. XP has issues with directx over multiple displays. I was running 2x monitors on a geforce 8500GT on 1 card and was having FPS issues due to the directx issue. I'm currently in the process of bulding 1 cpu that will have 4 monitors using close to the same setup as the OP, or I'm going to make 4 cheap boxes and go 100% hardware.