All Mac mini G4 have Radeon 9200 but the amount of graphics memory varies. They all work fine with 2D and 3D, however.
Most Mac mini G4s have 32MB. They're fine, but the system will resort is swapping graphics memory faster which will lead to some slowdowns. You may need to reduce the amount of eye candy with 32MB.
The so called "silent upgrade" Mac minis G4s have 64MB video memory. They're a bit rarer, but if you can find one they're well worth it. They also have higher CPU clock.
I personally have both 1.42GHz 32MB model (which I've overclocked to 1.58GHz) and the 1.5GHz 64MB model (silent upgrade). As a personal opinion, if you can find a great deal for 32MB model, just go for it. If you're more concerned about eye candy and want to have the best G4 Mini, then try to find the 1.5GHz 64MB model.
