Whatever it is, you're going to need an external soundcard to do anything serious. If you don't know why you'd need an external sound card, the internal one should suit quite nicely.
Yah, it's probably just a standard integrated sound card with a fairly average digital analog converter. If you really need to get good (audiophile or pro level) audio from it, just use the SPIDF out. You may also get a Firewire or USB sound card.