I agree that keyword search (with logical operators) would be most useful. I often have trouble deciding which genre to assign to a track (say, some of Walter/Wendy Carlos tracks from Kubrick's Clockwork Orange: classical, soundtrack, electronic...?)

BTW, several 'jukebox' MP3 organizer programs have a feature similar to this.

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green