The Wii is probably "the limit" of how good graphics are ever going to look on an SD or ED t.v., no matter what your playing PS3/Xbox 360/Wii even Xbox or GameCube, they are all gonna look pretty much the same overall on the older style t.v's.
You will only notice the differance really between each specific game, and maybe if you swap out for a really nice set of cables, beyond that there is a limit to what "computer graphics" can be displayed on an older t.v.
But once you plug these into a HDTV though its amazing! So much crisper and cleaner..We pluged Rock Band PS3 into my HDTV and wow computer graphics today are almost to the point with the physics/shadowing in it looks so close to real live video its amazing...
Without an HDTV though its only gonna reach so far on that scale and the t.v. will hold you back. When we plugged PS3 Rockband into the EDTV honestly it looked equal to Wii no better no worse,If it wasn't for lag calibration i would have never changed it at all... Thats not even a top of the line game graphically!