You were doupt' into getting a cable that your Video card can't recognize.
Ive got a cable that accepts s-video in that transfers it into yellow /red/white/ cable. composite.
It's made for my old Gateway TOWER's PC NVIDIA MX440 (5 year old). Kinda' proprietary stuff there.
Like holmes4 said they do make VGA to composite adapter boxes. Its OLD
tech that requires you to adjust picture from push buttons on the adapter box.
New tech would be the USB wireless adapters out there. Last I checked there were 3 good ones that transfered video from laptops to TVs (this was 3 months ago from an online PC magazine article). THese are around 100$ compared to the OLD crap 50$ boxes. When I want to Transfer TV shows or Movies to my TV set I do it through My XBOX 360 and TVERSITY , or Win7 Media Center. I prefer TVERSITY Its free and does it fast.
!!!THis is wireless and free stuff man!!!
as for getting your desktop on your tv, tversity doesn't work l;ike that.