If they download music off of ITunes it cannot be tranferred to a hard drive system directly due to the copywrite protection. A work around is to rip it to a CD and then load that onto the hard drive system. Also most hard drive systems will play MP3, some Flac, but none that I know of are compatable with the mac MP4a format which is the default music format for appples. I had to take a clients whole music collection from their Apple and run every album through a program to convert from MP4a to MP3 for an Escient once, took a couple of days to do.