Xbox360 running through Optical In on PC, No sound

Ok, first off I'm pretty clueless when it comes to the audio side of things. What I am trying to do is run the Optical out on my 360 to the optical in on my sound card and have it decode 5.1 and play the sound over my computer speakers. I thought this would be easy, was I ever wrong.

I have 2 souncards I've tried, both nice ones. I have a X-Fi Xtreme Music with the digital module add-on:
http://www.creative.com/products/p [...] 0&bypass=1
and a Bluegears bEnspire.

I first tried the X-fi, couldn't get anything working though, a quick search of the creative forums led me to believe that this was a lot harder than I anticipated, there is some pinout trick and whatever other garbage. I pulled it out and tried the bluegears, which I though would be simple since hardware decoding is one of it's touted features. But I couldn't get that working either. At this point, I either think I just don't know what I'm doing. Or there is some important setting I don't now about. Has anyone tried this, or is there someone who could walk me through setting up S/PDIF?

Ari