i discovered a corny but effective way to get MP3s to the music box. If you take an ALBUM and burn it to a CD-RW using WMP and WMP then reads the CD and recognizes the tracks you can take that CD and record it to the Music Box, which will pick up the track info. If you record an album to a CD-RW and WMP doesn't reread the CD track info it means it isn't readily available in the CD info database and it probably wouldn't do a lookup in the Music Box.this only works with whole albums AFAIK. It is a slow way to do it as you have to burn audio CDs and then rip them back, but it works.
It is pretty shoddy that the MUSIC box cannot store and show album art while playing. That would be better to see at a glance than trying to read the song title.