I'd stay away from any sort of usb headphone. How could a tiny generic usb soundcard sound good?
I got myself a pair of Sennheiser HD280 headphones and they are so nice it is crazy. They are about $100 USD so the price ain't bad. The zalmans will only be good on the comp bec of the 3 jacks, they won't be as good when usin them on an mp3 player or something.