Screw Xbox 360, my GameCube does "High-Def".
It’s not widescreen, but it’s in progressive scan on 90% of the Nintendo titles, and a good amount of non-Nintendo titles. Since I only have games actually made by Nintendo, I hopped onto eBay and got one of component video output cables and it looks crystal clear.
All you have to do is load the game up holding down the ‘B-button’ and it’ll ask you if you want to enable 480p. It looks damn good.
This’ll only work on older GameCubes (produced before May 2004) with the “Digital AV Out” port on the back. If you don’t have it, either grab a used GameCube with it, or wait for the Nintendo Revolution to come out.