Mac Pro Recording Sound Card

Ive looked through the forums, and its evident that since Mac Pro's have incorporated only PCI-E slots into their motherboards that obtaining a suitable sound card could be challenging at best.

My question is, considering the mac's core audio and all that, is a Professional quality sound card even needed? If so, does anybody know where I could find a good quality external FIREWIRE sound card?

here is some external sound cards for macs
http://centerstageproject.com/audio.php

Thanks for the link. That Griffin FireWave caught my eye...I might check into getting one.