I bought an adapter like this off of ebay.
VGA to S-Video/RCA (Composite) Adapter Cable
It is a 15 pin male on one end to plug into the video card, and has both S Video and Composite video (Yellow) connectors. However, you still need a cable to connect the S Video from the TV to the adapter.
I'm trying to do something similar, only with the composite connection, but I'm having problems getting an image to appear on the TV.