This Christmas my wife and my parents bought me a video iPod that while it certainly is the coolest thing in the known universe, it unfortunately doesn't do Firewire, only USB 2.0 connections. My Quicksilver PowerMac G4 (purchased in 2001) doesn't have USB 2.0 on it, only USB 1.1 ports. Having put a USB 1.1 PCI card in the G4 earlier, I decided to take it out of the Quicksilver and put it into my children's B/W G3 (swapping it for a USB 2.0 card that I had installed into the G3 last year). After I put the USB 2.0 card into the Quicksilver, I connected the iPod and tried to transfer nearly 19 gigs of music and videos to it. It took over 3 hours...closer to 4 if I recall correctly. I decided something wasn't right so I went into Apple System Profiler and found the ports listed as: 
USB Bus 
 
The USB 2.0 ports on my Powerbook 1.67 GHz are listed as: 
USB High Speed Bus 
 
Long story short, it turns out there are two different specs for USB 2.0. USB 2.0 and USB 2.0 High Speed. I ordered an IOGEAR USB 2.0 high speed card from http://www.macsales.com and put it in the Quicksilver. I connected the iPod, reset it erasing all the data from it. Opened iTunes to synch it and...28 minutes later the entire 18.8 gigs of music and videos were on the iPod! 
 
I love progress. : ) 
 
Moral of the story- If you buy a USB 2.0 card, make sure it is labeled, "High Speed."