If you looked at the Wii’s hardware statistics you might have noticed that it’s max resoultion is 480p, which might be bad for people with HDTV as they might not be able to play their Wii very clearly (this is because the RBW cables that you get are analog cables and HDTV is HD not so much analog). For the best graphics picture you should use component cables for the Wii. But the only problem is that the component cables needed are not included. And they cost $30 bucks from the Nintendo Online Store (only place to buy them for now).
And the GameCube ones don’t look like they work for the Wii (the part that connects the cables to the system looks way too big) so you either can wait for MadCatz to make their version of the cables (December 1st) or you can buy them now and wait until Novemeber 28, 2006 to get them.
The Wii will still function on HD and ED TVs but you will not be able to use Progressive Scan and the quality will not look good.
You can buy the cables here.