How can I join HD-TV to g-card with sapphire HD pro installed

Hi there,
The sapphire HD pro I have installed in my g-card came with an s-video output. The card has the colors blue and green on it. Now, I want to join it to my HD-TV. Can I go ahead with the union so that I could use my vista media center? What am I missing here? Thanks for helping me out.
