A standard s-video cable should plug directly into this port, since your tv supports s-video, just grab an s-video cable and plug it up. Run the AVWizard and press 2 (might not be 2 for s-video, check wiki) to get it to show up.
The video card usually comes with an adaptor to convert the 7 pins to component or composite if needed, but for just s-video, all you need is the cable.
edit:
if you want composite instead of s-video, make sure your card didnt come with a cable that converts it, but from what you described, a standard s-video cable will work perfectly fine for you