For the comparisions, I used two televisions: a Sony KV-27TS29 (27" 
direct view, glass delay-line comb filter), and a Pioneer PD-4683-K (46" 
rear projection, 3-line digital comb filter). The Sony has only 
composite video inputs, and the Pioneer has both composite and s-video 
inputs.
  What's different between the composite and s-video inputs? With 
composite, the luminance and chrominance information of the video signal 
are combined into one "composite" signal. It's up to the television to 
then split the two back into their component form, commonly using a comb 
filter (or a notch filter in some televisions). The quality of the 
seperation is dependent on the quality of this comb filter (although 
none of them are perfect). S-video keeps these two parts of the signal 
seperate along the whole path, preserving the integrity of both. Keep in 
mind that the advantage of s-video only applies to non-composite video 
sources. Laserdisc and VHS both store the signal as a composite one, 
which means a comb filter somewhere in the chain is a requirement. DSS, 
S-VHS, and (eventually) DVD store the components seperately, and thus 
are able to take full advantage of s-video inputs. The PlayStation can 
also be considered a "component" source.
  Using the Sony television (composite input, obviously), sharp, 
high-contrast edges would often exhibit a "zipper-like" pattern. Perfect 
examples are the two opening title screens - the "zipper" seems to crawl 
around the edges of the gold diamond and the red "P." I've since learned 
that this is the direct result of the type of comb filter in this 
television (glass delay-line). Once you know about it, and know what to 
look for, you start to notice the zipper pattern all over the place 
(watching the Simpsons, around the score in basketball games, etc). 
  Using the Pioneer television and composite inputs resulted in almost 
no evidence of the Sony TV's zipper pattern. It would show up 
occasionally where there was a great deal of thin, sharp, highly 
detailed edges. The two opening PlayStation screens did not exhibit the 
offending zipper patterns at all. Obviously, a 3-line digital comb 
filter does a better job than the comb filter in the Sony. 
  Connecting to the Pioneer via the s-video input resulted in a complete 
disappearence of the evil zipper pattern, as well as noticable increase 
in the sharpness of the edges. The gold diamond and red "P" had a 
definite termination, whereas with the composite input their edges were 
a tad bit fuzzier. 
  Is the difference worth the $30 price tag on the s-video cable? For 
this size of TV, I would say definitely. If your TV has anything less 
than a digital comb filter, you should notice a profound difference, no 
matter what the size of the television. But if you have a medium-sized 
TV (27" or so) with a digital comb filter, you might not notice any 
difference at all. Of course, if you have the $30 to spend anyway, it's 
also a cooler looking cable than the composite ones (it's a big, thick 
grey thing with some heavy shielding on it!). :)

Adam
adamwh@ids.net