AFAIK, s-video is a seven-pin system. Whatever you're looking at that
has four pins isn't s-video. Presumably you can find a s-video to
whatever adaptor.
s-video connections carry video only, no audio. So yes, you'd need a
second cable for the noise.
S-video is actually 4 pins (Chrominance, Luminance, and 2 Grounds).
Your laptop may have something similar to the one shown at:
http://pinouts.ru/VideoCables/ati_vidcable_pinout.shtml
(note that there is an S-video connector shown there as well)
The connector on your laptop may also include audio signals, or may also be
able to be used for composite and/or component video. If you can look up
your laptop manual (perhaps online?) it may tell you this.
It is quite possible that a standard S-Video cable may fit the connector on
your laptop and connect the video signals correctly to your TV. Some have
a small rectangular plastic pin that you may have to break off to make it
fit. It won't provide an audio connection, though. You may need to find
the correct adapter cable for this - or use the headphone jack. Check with
your friends that have bought a new video card/computer - these sometimes
have such a cable included that may be the right one for you. I've thrown
away hundreds of these at work that we don't use - most of the newer ones
seem to be component video ones (3 video and perhaps two audio).
Instead of S-Video, you may be able to find an adapter to give you
composite video (a single RCA connector, usually yellow). If your TV has
an S-Video input, it quite likely also has one of these.
NOTE: it is possible that using the wrong cable may damage something, so
you should try to make sure by finding your laptop manual. The nature of
most TV/Video signal connections is such that damage is actually not all
that likely, though - they are expected to be plugged in by non-technical
people groping in the dark behind a TV.
