Erm....
Excuse me for being dumb, but why not just stop using FAT32 and use ext3 (or one of the other file systems) - TomTom could include a driver for the chosen FS as part of their 'Home' software package, or even include it on a separate drive built into the TomTom itself.
Paris - 'cause it seems soo simple, yet probably isn't!
Biting the hand that feeds IT
