I tried a V3XT (on a standard TV) and I have been unimpressed with the results. You can check out my thread in this forum (which has a link to the original thread on htpcnews).
The XGI Volari V3Xt comes with a component cable that converts the s-video jack to component. Supposedly, the port natively supports component out, so it isn't just converting the s-video signal.
I got mine from triocomputers, but search around and you can probably find it for a better price and lower shipping. They bent me over on the shipping charges and thier sales department wasn't exactly run by the nicest people.