Problems with sound card/driver

I got a new motherboard about a month ago due to my old one failing and have noticed sound problems since. The sound often skips a little during songs/speech and when playing certain games the sound effects will cancel out the music. If i connect this http://dx.com/p/usb-virtual-7-1-chan...-adapter-59077 cheap usb sound card the problem is fixed, but the sound quality is much lower.

The sound driver is listed as "VIA HD Audio" and this http://www.via.com.tw/en/products/audio/codecs/vt2021/ is the codec listed, but i can't work out what driver updates, if any, i can install for it.

I'm running Windows XP