I bought an chintech 7.1 PCI with digital optical out. It was only 25 bucks and the sound is pretty decent. The cons is that you must have a software decoder to use DTS like Win DVD Platinum with DTS support (pretty easy to find), and also I use my sony receiver where I have hooked up my speakers. So if you have a receiver that would be your best budget bet. Buy it at New Egg.

Users of the Chaintech AV710 have a huge user support base to learn from. Many claim the AV710 is greatly enhanced by using Via's reference drivers, here's but one guide floating around showing how to apply the Via drivers: http://www5.head-fi.org/forums/showthread.php?t=75655