Looking at the back of my cube the port on the Wii definitely isn't the same port they used for SNES, N64, and GameCube. It resembles the Digital A/V out on the cube, but sine the Digital on the GameCube didn't support Audio (which makes me wonder why it says "Digital A/V Port" above it when it was only video...) so no GameCube cables will be compatible, whether you're using the component, composite, or s-video.