I've got a M-Station in the car with a 20 Gig drive and have stored in the directory based format - artist/album/track.mp3?
I used to have a higher level for genre but it was frustraiting haveing to navigate all the way up and back down to hear music from the same artist (esp whilst driveing

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If you give a folder for each album its then possible to repeat folder or add a whole folder (album) to a playlist. If you put all the tracks from one artist under one folder, then this becomes difficult or you end up using playlists to define albums.
Ed