Don't let 480p hold you back just because Nintendo's Wii doesn't output high definition visuals. Using the Dolphin emulator for PC, Mac, and Linux that runs GameCube, Triforce arcade, and Wii games, folks over at the NeoGAF forums are cranking out high definition screenshots of New Super Mario Bros. Wii via Dolphin that look absolutely stunning in an upscaled sort of way. Check these out (and click on 'em to see them in full resolution).
I love the look of this game turned up to HD, but as some at NeoGAF have noted, New Super Mario Bros. Wii upscales a little too nicely, almost as if it were designed to be backwards compatible with a future Nintendo console that can play legacy Wii games in high definition without turning the experience into a fuzzy mess. I can see the sense in that, but if this is the case and the company is playing a long game, then I have to give Nintendo credit for spending the extra time and resources to design HD-friendly character models for a console that cannot display them to their full potential.