Just an S-video cable and if you want audio on your TV, you'd have to get a mini jack-RCA adapter and plug the audio cables (red and White) into your TV.
Another great thing I use with my s-video. if you have an ati card, they have this feature called theater mode where if you set it up (really easy, just one setting) it will automatically display vidoes on your computer in full screen on the tv even if that vidoe window is not on top. as long as its playing on the desktop it shows on the tv. doesnt work for flash players though like on youtube
I am a car audio installer. I work for a shop that sells lots of home theater equipment.
The S-video or super video plug is a video output just like the AVG or DVI outputs on your video card. However s video is most often used in home theater applications. Virtually all modern day TV's costing over $250 will accept this plug. You can use the video output to connect your video card to a TV or projector. You can also use the AVG or DVI outputs to connect your video card to a TV or projector too.
Generally in home theater applications the video quality is as follows:
-Coaxle (the cable that your "cable" comes on that you screw into the back of your TV) = poor quality
-Composite video (this is the yellow plug that is next to the red and white plugs on the back of DVD players and many other devices) = slightly better quality then coaxle
-S-video = medium quality
-component video (this is the red, green and blue plugs found on the back of some DVD players and HD satellite receivers). = good quality. Ability to be high definition
-DVI / HDMI (Digital Video Interface / High Definition Mulitmedia Interface) (found on the back of expensive DVD players and some high end satellite receivers) = all digital signal. Best quality.
So basically it goes like this:
Worst quality
Coaxle
Composite video
S-Video
Component video (has ability to be HD)
DVI / HDMI (has ability to be HD) (digital)