There are two different things that you can choose to do.
Option one - Use the PS2 wire to hook the sound directly to the surround system.
Take your video wire (yellow) and plug it into your TV. Then, take the audio cables (red and white) and plug them into the 'IN' slot that is on the back of the surround system reciever.
Option two - Buy a cheap audio cord (red and white)
I.E.
http://www.circuitcity.com/ssm/GE-Au...oductDetail.do
That one is a little pricy, but you can easily find a similar one at WalMart. In this one, take all of the wires from the PS2 (red white and yellow) and plug them into your TV. Locate the "Out" ports on the back of your TV, where you plug one end of the audio cord into. Then, you plug the other end into the "In" ports on the back of the reciever.
Hope this helps..