Q: mini dvi to s-video/composite adapter doesn't seem to work?

basically i'm trying to hook my rather new 2.53 ghz mac mini to my tv, which basically has rca inputs. so, having seen several laptops hooked to this tv as simply as using an s-video to composite adapter, i figured it would be as simple as getting the mini dvi to composite adapter and i'd be good. well, for some reason this doesn't seem to do anything. the other weird thing is that when i hook the cable from the composite adapter to the tv, i get a buzz out of the speakers as the connection is being made. why is a video signal having anything to do with the audio? plugging my playstation 2 into the same input works fine. why the difference?