first off, here are what the 3 main video interfaces are:
component: 3 jacks of colors red, green, & blue
S-Video: one jack with 6 pins & a plastic guide stub
composite: one yellow RCA jack
& the quality ranking is as I have them listed above with component being the best of those 3. From a dvd player... you might not notice a difference using component until you enable progressive scanning mode (otherwise known as 480p). Be sure your video output device (TV or whatever) can decode & display a 480p signal before you set your dvd player to deliver such a signal. Usually such a setting can be found in the video options menu (or whatever your specific dvd player calls it) which is usually reached using the remote.
I used to watch DVD's using the simple Audio/Video cable. I recently bought a new flat screen TV which had the Composite Video In capability, I have connected my Sony DVP NS305 DVD player to my TV through the composite option, I don't see any difference between the two, please tell me if composite video is better than the simple Audio Video interface, and also if S-Video is better than composite or not. Thanks.