In short, I doubt there is to much of a difference other than the Klipsch would make you not want to listen to music on headphones and the Labtec would.
If you mainly use your headphones just plug em directly into the sound card. Get a splitter, plug headphones into one jack and speakers into the other. That would probably give you the best quality.
<A HREF="http://www.folken.net/myrig.htm" target="_new">My precious...</A>