I have a couple of 16GB cards, and one of those filled gives me 3 or 4 days of continuous music on shuffle without any repeats, going 24 hours/day. That's longer than I care to drive. With my bluetooth stereo, I can start playing by pushing one button, and have it pause, mute, and answer the phone if a call comes in. Ain't no way I'm going to futz with a laptop to stop the music while I'm driving.