i'm a pretty hardcore geek but do not know much about gpu technology. I have a G4 sawtooth 500 that I use as a media center and it only has a Rage 128 pro 16mb. very soon I will be upgrading the cpu to a G4 1ghz and would also like to upgrade the agp slot to a better card.

the main thing I am wondering is if a better card would really help me. all I do on this system is watch divx, dvd, quicktime and listen to music with itunes. would a newer vcard help me? will a modern tech vcard render video better or will the faster G4 cpu be all I need?
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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