Hmmmm. I took a look at the Sound2MIDI Website, and the product does look interesting. It converts only from a single source that plays or sings one note at a time, so you can't pick out a melody from a CD track unless you can isolate a single instrument.
Don't think I'll bother trying it, but I'd sure like to hear a report from somebody who's had experience with something like this.
-Joe Offer-