The real minimum GPU for smooth MP is an AGP ATI 9500pro (4 pipe) running on an AGP2x bus.
Anything above this and you shuld have no problems. As for NV GPU, if I remember correctly the ATI 9700 series was so good that NV needed to be the next generation above this to match performance.
Anything above this and you shuld have no problems. As for NV GPU, if I remember correctly the ATI 9700 series was so good that NV needed to be the next generation above this to match performance.