I recently bought a 30GB Nomad Jukebox, which is a laptop HD-based MP3 player. My question to those in the know and those who own iPods and similar devices is: how do they react during things like bike-riding, jogging, any sort of general excersise where the player might find itself crammed in a cargo pants pocket and exposed to some slight jostling? Generally, the HD itself isn't spinning - it only does it as much as is necessary to cache music to the flash memory within the device. Still, is this enough movement to damage the HD? Thanks.