1. Avoided Destiny offers MP3s of most Mario Bros themes, including the Starman/Invincibility theme. I'd been looking for this for some time, and The Mushroom Kingdom was surprisingly bereft.
2. Alaina has an Nike + iPod Nano Sport Kit, which I've written about a little bit and Alaina has covered as well.
3. I'd had no success converting any of the (many!) starman.mid files into acceptable approximations of the original theme. Mostly, these were recorded with piano set as the default instrument, and the result was some nasty jazz-ified versions of a classic theme.
4. With the availability of the Starman theme in MP3 format (see #1), the cycle is complete. It's now possible to set the Mario Invincibility theme as her Power Song. Expect incredible speed boosts.