The B&W G3 should work with all 3G, 4G, and mini iPods. It is officially supported, but all those iPods require 10.2 or later. They won't work with OS 9. However, the B&W G3s are known to sometimes have flaky Firewire ports because Firewire was brand new when they were released. It's very possible that your Firewire is just not working right. Do you have any other Firewire devices to try out? It might be a good idea to just get a Firewire PCI card, as it'll be more reliable than the built-in Firewire.