Looking for better sound from my Dell XPS

Hey guys, I have a old school DEll XPS which has a SigmaTel Audio sound card. I have this notebook hooked up to a Klipsch 2.1 system. Sounds ok but want to either get a new sound card or external DAC. Please help. I'm an idiot when it comes to this stuff : ) Thanks.
If your budget it's tight (or not), I strongly suggest you to get an EMU 0404 USB 2.0 interface. It has a good internal clock (that reduces jitter) a great DAC, and it's 24/96 capable via USB. I had one and I loved it. For about $200, you won't have many better choices.

I forgot to mention that the EMU works with ASIO plugins, which allow you to by-pass the K-mixer and get bit-perfect digital audio out of your computer. I suggest you to use Foobar or Media Monkey as media players.
Thanks Lucho.
Get a soundcard. there are good brands like asus, creative etc.
If you are a music lover, you can get the ASUS Xonar Essence STX.