It wasn't the first mover advantage with the 1.8" drives that made Apple win- although that was a necessary ingredient. You can see this because the device didn't get popular right away. It was the second mover advantage of iTunes, which avoided the first mover's problems (Napster) that led to Apple's dominance. Apple went with closed tech on the iTunes store, which combined with device lock in to drive the iPod success. It was as if they had all of the music, and you could only play it on an iPod. They made the player compatible with MP3 (the open part Stringer refers to) so you could use all of your old Napster downloads easily, and made the iTunes client capable of ripping CDs easily. Once they made the iTunes client available for Windows it was off to the races. The iPod is a great design, but on its own, it would not have been dominant.