Glad to hear things went well with your upgrades speedmike!

One thing you can do to improve playback of video is use mplayer and activate a feature in preferences called "slow frame rates on slower machines".  Although it does lower the framerate it makes playback a lot smoother.  Back in 2003 the only mac I had was a B&W 350mhz and it was able to play high quality avi in a very tolerable way.  So with mplayer and that feature enabled on a G3 1ghz you'll be golden.
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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