Mario Kart is actually the first (and only) Wii game I tried and it looked pretty damn great, so that kind of helped ease my fears. From the research I did online, I think the component cables really help the Wii on an HDTV.
Though I did run into one problem and that is the virtual console games look like crap. They range from kinda bad (Super Mario Bros.) to downright horrible (Donkey Kong Country) and the fact that the TV is a 52" certainly doesn't help matters. Anyone know if there's a way to lower the resolution when I play the old school games or am I doomed with super-pixelated graphics?