A few questions about sound cards

SPDIF depends on which variety you have, but both serve the same function. Either you have optical (fiber optic) or rca-style. Either way, if it's an OUT, then it goes from your computer into a receiver or other device that has an SPDIF in jack. Think of this as a super-connector for your sound that looses no signal and has no distortion across the length of the cable (better than 0-oxygen solid copper). It can transmit sound in up to 8 channels digitally, so if you dont have 5.1 or better speakers hooked up to your computer, you can use the surround sound in your home theater or stereo, whatever... You will have to set some parameters on this if you use it such as the digital sampling rate, but most cards have all of this defaulted to industry standard settings that will be compatible with most receivers. It's not complicated.

If it's an IN, then its for receiving and decoding digital sound signals from another source (external DVD player, home theater receiver, etc.). This is usually for the reverse situation where you want to hear the Dolby or whatever through your computer speakers and maybe you don't have a home theater system. Most sound cards dont have an SPDIF IN

You dont have to worry about the CD in connector on the drives. These are more of a legacy feature for older drives that allowed them to play CD-Audio (only) cds from the drive independently from the computer. (at least to my knowledge the rest of this is true...) I don't think that this ever really caught on (remember the PLAY button on the front of some CD-ROMs?). All of the music played off of discs these days are done through a software interface like MediaPlayer, not independently of the OS.

Yes, you can connect it to your TV. Go to Radio Shack and tell them that you want a STEREO 1/8" male jack that has 2 RCA male jacks (female if you need to extend it beyond the reach of the converter cable) on the other end (red and white). You plug the 1/8" jack into your sound card, then plug the RCA's into your TV. The cable probably wont reach, so you'll have to buy an extension for the RCA's (Male to Male).

Or, if your TV has SPDIF IN, just buy an optical cable (if it's optical and you have an optical out) or a SPDIF RCA style cable (only one plug on each end=orange color) and run it to your TV from your SPDIF OUT on the sound card.
WHEW!!! 8O

got a question about this actually. i got a system running an audigy 4 on XP, and i have a yamaha 5.1 reciever, but im not sure if it has a SPDIF-in. is SP-DIFin the same as coaxial audio? im currently using a splitter off the front speaker jack to send front channels to both my PC speakers and reciever - which is recieving stereo signal)

i dont want to go and spend like 100 dollars worth of cables to find out it doesnt work. (its like 50 feet from the pc to the tv)

Or you can just look up craigslist.org. Plenty of people making custom cables for cheap. The stuff ain't rocket science.