Soundcard confusion.

Recently started using audysey to record streaming music. Computer has Realtek AC 97 and I am thinking that it can be improve on. Also I go back and forth between home and office doing recording on both computers. Thinking that a usb soundcard might be the answer but which one? Playback is through squeezebox to dac to receiver so guess the soundcard will be mainly for the recording process.
I will be archiving concert dvd's soon and would like a card that will handle at least 5.1.
Suggestions?
Thanks
Steve