For anyone who's interested in adding a card, I couldn't find anyone else who had recommended a card here, so here's my experience (I would post it up at xlr8yourmac.com but they have no section near as I can tell for add on PCI cards.)
My Brother and I have virutally the same machine. G4 Sawtooth. He got a Video iPod as an early Christmas present. He was still stuck on the onboard bus, and moving much to the iPod was slow and frustrating. So I went to NewEgg and found the cheapest card there that said it was compatible with OS X.
It was the "Koutech PCI to USB2.0 Card Model IO-PU520 - OEM" It was $9.70 plus shipping was something like $5.00.
It came, I plugged it into the third slot (first was AGP, second was occupied by a USB 1.0 card left from the previous owner. I was a little concerned because other cards sold at NewEgg seemed to suggest they needed 10.3, and my brother is still on 10.2
Anyway, I started up the machine and ran a speed test. I transferred a 170mb file to the iPod (just drag and drop). On the onboard USB (1.1 I believe) took 4 minutes, 4 seconds.
With the new card the transfer took approximately 16 seconds.
I'm happy with the card. If anyone needs a USB card, this one is as good as any.
Only thing i can figure is, why on earth they would put a port on the interior side of the card. What purpose is there plugging a USB cable in on the inside. I guess I have the same question about why apple stuck a FW port internally on the sawtooth MB.
Edit (once again, I managed to put my post in the wrong forum. Can someone move this to hardware?)