The Audigy card, while popular, does not have very good FireWire capabilities. Creative decided to not follow the IEEE1394 standards and instead created their own (SB1394). While the newer cards (AudigyII) seem to be better, you may find that your card does not work with the iPod. Try a different card.
I have Audigy SoundCard with a SB1394 Firewire port. My PC isn’t recognizing the iPod. Why not?