I have a SBLV, and I'm not sure, but I don't think this sound card has a digital out on it. You would need a card with some sort of digital audio out, possible optical. Something like This.
That's right. I had the same card and the only way I was able to get 5.1 through my receiver was with the addition of a Hollywood Plus card that did have a digital out.
Many lower end soundcards do have digital out, in the form of a 3.5" headphone jack sending a digital coaxial signal (usually combined with an analog output. IE Rear Surrounds/Digital). To get the signal you have to enable it in the software, then buy a 3.5" to RCA cable.
Because it was going to be close to impossible for me to maintain a permanent digital connection with all the various audio codecs I kept using on my system, it was easier for me to build a series of home-made audio cables and connect them all to the multi-channel input of my receiver.
However, you can't use just any headphone connector on your sound card. Because the jacks on most sound cards are spaced so tightly together, most audio connectors out there will not fit on most sound cards all at once because they'll be too wide. And forget using those cheap cables you can find in most big box stores and filing down the width of the plastic jacket. I tried it, but those cables were so bad that I was getting serious cross-talk problems between the channels!
To get quality cables, I had to build my own using Canare's four conductor L-4E6S microphone and audio interconnect cable, eight high quality RCA plugs from a surplus shop, and three headphone plugs from Radio Shack part #274-869 (take out the screws and solder the wires to the connectors -- much easier and more solid). One of the three runs was split into four RCA plugs instead of two so that I could plug the left and right channels to one of the other audio inputs on my receiver and use the Dolby Surround decoder on them when appropriate.
It too a lot of work and heat shrink tubing to splice all those wires properly, but it all works now. And I don't have to fight with the computer to get the codecs to work with the digital output.
I've used the digital-out on my SB Live when listening to DVD movies for quite a while, but have never known how the multi-channel games work... for instance If I want to play Call of Duty or Doom3 with multi-channel, does the card encode the multi-channel output digitally and pass it through the digital-out? Or, do you need a soundcard w/ 6-channel analog outs?