I tried an ATI 9800 pro, and the tv-out was not very impressive. the drivers also didn't give it many options. My friend's sapphire 9800pro is similar.
My old Abit Geforce4 ti4400 using the 41.09 drivers has awesome tv-out for both games and for movies. great color, proper ratios, overscan support.
the newer 53.03 drivers seem to have some issues though.