Hi, I've got spdif output from my shuttle xpc mobo, I'm not sure about the DD and DTS but I think it does. I use it to play sky recording dvd copies and mp3's etc through my AVR and the sound quility in comparrison to the normal line out to the same AVR is great! A lot clearer and fuller sound with good deep base.
Are you building a new PC? or upgrading your existing one with new mobo ram etc?