Devil_warrior, is that really your system?? I never seen anyone with dual 6800 Ultras lol. Since you can afford something like that. Why dont you just get a creative labs 7.1 suround sound system?
You will need optical output to your stereo or something similar. And a home surround sound system will not have the same connectors that a computer surround sound system has. If you have optical out on your card and optical in on your reciever (or coaxial/digital) then you can do it.
There is a few ways you can do it. Run Digital Optical/Coxial out from computer to amp. However this will only result in stereo and not True surround sound. For true surround sound you would need to use the 1/8th jacks to RCA and plug them into a 5/6/7 channel input. The channel input is not on all amps.