If you plan on using your computer as the source (I do the same), then I would highly recommend you buy a new soundcard.

I personally use the M-Audio Delta 44, and it's sound quality is truely amazing. I use it in my home studio, so an average listener would probably not need something like it (1/4" 4 in/ 4 out). But, I would still recommend other M-Audio products.. The M-Audio Revolution 7.1 is definately a good card, at a very reasonable price of $120.00 USD.