u have a PCI express mobo???
okay than.
I'd suggest the 6600's. same price, but it's basically better architecture. THe ATI x series are basically just revived ATI 9 series.
6600's are brand new baby. and chances are, the 6600 architecture might include a 12 pipelines GPU, thus giving you a chance to softmod the sucker into a 12 pipeline card. not sure ATI can do that. hehe.
i'm a NVIDIa fanboy, but only for this generation, was an ATI fanboy for the 9 series.
but u'll be happy with the 6600.