If you really want to hear PC Audio at it's best, go firewire. I just went to a firewire to spdif converter (M Audio Firewire Solo) and just couldn't believe how good it sounds. There's just no way the power supply in a PC can provide stable, clean power to a soundcard. I was thinking of going USB but thought best to just go with the fire wire.
Enjoy your rig.
Enjoy your rig.