So what is the *name* of this cable if I want to order one? And are the connectors the same on the analog and digital versions? (I'm guessing they are.) My mobo contains sound-card facilities (mediocre), and I think the mobo jack has 4 pins in a line, surrounded by a plastic enclosure.
I believe they are referred to as CD_SPDIF, that's what i've known them as. I've never had to order one, though. The sound cards i've bought (Creative Labs) have always come with the cable.
The connector of a CD_SPDIF is different from that of the CD_IN. So, to attempt to help you further, if you want to connect the four pins on your sound card to your optical drive, look for a CD_SPDIF cable.