I have never heard of a Radeon 9600 PCI.  Even if there really is one a GPU like that would be wasted on a 66mhz bus.  Even the 9200 will be wasted on a bus like that.

The 7000 is a good card for these machines.  Cheap, easy to find and you won't be wasting money on gpu power that the graphics bus will not be able to utilize. 
_________________________
Mac mini C2D 1.83GHz - 2GB RAM - 200GB 7200rpm HD
Sawtooth w/G4 1GHz - 1GB RAM - SIIG SATA w/2x1TB HD
B&W w/G4 600MHz - 1GB RAM - 2x80GB HD
Sawtooth G4 400MHz - 512MB RAM - 40GB HD
Dell Ultrasharp 2007WFP 20" Widescreen LCD
2.94TB Total Storage