They *are* ruling the market. Name a more popular portable music player.

If you're talking about their computers... well, there's lots of reasons for that...

#1... they have a lot of ground to make up from lots of very stupid executive decisions over the years in terms of pricing, marketing, etc.

Until now, you could buy or build your own PC for a fraction of the cost of any of the macs; you can upgrade your PC for a hundred bucks, but you're pretty limited in how you can upgrade a mac. A lot more software is published for PCs than for macs (a not insignificant portion of the crowd that are devoted to their ipods also are big fans of some kind of software that won't run natively on a mac)... and you can buy PC parts everywhere.

I have a lot of respect for the choices apple has made of late (an entry level mac for instance), but they've got a lot of ground to make up. It's that devotion that has even given them the chance to make the good decisions they're making today.