PS3 spdif to spdif in on Diamond sound card

[isaacjade]

I have a 32 inch monitor which I use for my PC and my PS3 so I have my PC speakers sitting right there. Instead of buying a new receiver to put the PS3 sound through I bought a Diamond Xtreme sound card with spdif input which converts and sends to analogue out. In other words I can connect my Directv receiver to my PC sound card using the optical audio cable. The sound card converts the dgital info from the Directv receiver and outputs it as analogue audio through my PC speaker system. (My PC speakers kick ass)
For some reason the computer does not see the sound coming in from the PS3. Does the PS3 need to send in a specific format to be picked up by spdif input on the PC sound card? On the PS3, when I select fiber as the audio option I am presented with about 15 different formats and am not sure which one(s) to choose.
Anyone else outputing PS3 sound through the optical cable to a PC sound card in order to have PS3 sound play through the PC speakers?
Any help would be appreciated as I am hoping I didn't just blow money on a sound card that won't do what I bought it for.
THX