if u use the MSC connection then u can sync with ur music library using a software called
u can define folder to sync on ur PC and on ur ZIP and sync.
it supports 2 way sync and 1 way. and the option to propogate deletions on the synced side.
meaning, if u downloaded a song on ur PC and placed it in ur music library. u can plug ur ZIP and sync the new files/folders to it.
the same image of folders and files will be copied to the player.
also, lets say u have downloaded on another PC copied to ur player and then came home. u can sync from ur player to ur library on the PC.
works wonderfully, its free and saves alot of pain if u keep ur library fresh with new stuff 
hope this helps
