I also found out something. I listen to a lot of Audio books myself so they have to be in order. I have all MP3's. They were named as such:
Folder: Christopher Paolini 1 Eragon
Files: Eragon 001.mp3 - Eragon 125.mp3
Folder: Christopher Paolini 2 Eldest
Files: Eldest 001.mp3 - Eldest...
