The classic games *are* played under emulation on the Wii as far as I know. There are no changes to the original games in graphics or sound.

One could easily play nearly all NES and SNES games on the Wii. I wouldn't want to do that of course, but there are are certainly a few select titles that will be interesting. Gamecube titles will be more appealing of course - and for those you just need the original disc and a controller.