my portable mp3 player (& wma, wav, aac player) did not play those located under artist/album folder scheme. if I choose "dont create subfolders" then it uses root folder (\) but I want it to...

Good Day! Does anyone know how I can make a mobile device map to a drive letter? I've got a Creative PMC (Zen) and I would like to use part of the 20GB to act as an external drive to put some data...