I've been playing around with composite and I have to tell you that on most TV's there is serious dot crawl when using composite from the TV out card on your computer. If you still want to use your TV with the "one rca plug" (aka composite), then you want to go the S-Video to RCA route, instead of using that VGA to TV adapter.
The VGA to TV adapter is only for video cards that know how to use it, and is wired in a wierd way. I have tried one out with a few cards and have yet get a usable signal

You can probably also go somewhere like radio shack and buy a s-video to composite adapter, and if your technically inclined, you can build one:
http://www.epanorama.net/circuits/svideo2cvideo.htmlgood luck.