Most on board sound cards are not worth the PBC they are printed on. They are plagued with low quality chips and interference from other internal components. The best solution would be to go with an external fire wire solution. I and a lot of others in our forum use one of the Echo AudioFire series of sound cards. These primary application for this series is professional audio but they make an amazingly crisp sound experience, but for your desktop.
I guess it would be possible to tote around the AudioFire2 but it is not an elegant little device like the Turtle Beach Audio Micro USB sound card. It is small enough to almost be considered a dongle or even a larger headphone jack adapter that will rival the sound quality of the pro audio FireWire sound cards. Though there are a few caveats- read on for the full scoop.