Originally Posted By: "maestro "

You could sell the G4 psu and pick up a PC ATX psu for cheap.  Most will fit.  I have used ati 7000 and 9200s in G3s with success.  A 7000 is plenty for the work that a G3 can do anyway and they are super cheap.  You will need to do some cutting on the case, but I say go for it.

I bought an ati 7000 on ebay for $18
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