Designing a half-linear filesystem would be nice indeed.
but when a file is deleted, a gab excists which only can be filled with a smaller file.... well thats not realy a problem since deleting mp3's doesnt happen too often right(?)

I haven't considered apple filesystems yet,, but i assume that these will be more advanced then the dumb dos(fat) aged file system. NTFS would be a other reliable option.

Well Fat32 was my first choise regarding overall compatiblility... I assume most readers would agree with me on that. Its nice to unplug your 1 to 128 gig drive, and hook it on your 8bit microcontroller, and let it play music for the whole week till the car battery is dead ;) And then ofcourse while recharching you can plug your drive back into your computer, and play the mp3's from there again 8)

HEh,, i only have like 300 mp3 files ;P
dont think that im a mega mp3 ripper or something........