In Windows Media Player you can edit the song title, album, composer, artist, genre, year, contributing artist, parental rating, and rating. Maybe more, but these for sure. Do you need more?
Dave, have you checked out Audacity?TD
I like the NCH stuff, but I wasn't aware that any of it was free after the trial.
I use MP3tag, it is freeware and I think it does everything you need: http://www.mp3tag.de/en/index.html