Just get a sound card with digital spdif outputs and use a reciever (home or car) with digital coax inputs. Run one cable for 5.1 channel, pure digital sound, ahhhhhhh. Surround sound games never sounded so damned good.
I used to do something scary. Iput together a cable out of radio shack pieces, The Fraken-cable, that took the two speaker outputs of the SB Live, split, and ran em to the 6 channel input on the back of my old Pro Logic reciever (had to split it in to sub inputs too). If was a big, confusing, ugly thing.... thank god for digital coax