Depending on what you actually DO with the sound you might be able to use onboard sound! Some nForce2 boards come with a great audio processor called the nForce APU.
For output do what the last guy said, use a splitter cable. These are quite common and originally used to connect portable CD players to home stereos. They have a stereo 1/8" jack on one end and R/L RCA connections on the other. They're usually 3 feet long.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>