I dont use a mac, but I dont knock it. They are made to have everything built in and to work right out of the box. For people without the time or energy (The rich and/or the old) they are fine. For people who actually know how to use a computer, prefer a two button mouse, and perhaps like to play video games, a cheaper PC and a little set-up time will do just fine.
If you watch the apple computer (not the ipod) commercials carefully, the market is the actor playing PC. The aging hipster who thinks he can still communicate with his kids if he just buy an expensive but easy to use computer. Ironically, he thinks that if he bought a cheaper PC and had to ask his kids (and actually communicate with them) for help setting it up and using it, the endeavor would be less sucessful.
The ipod on the other hand is marketed to kids who probably have PCs... or access to their parents Macs. If they already have PCs that's ok, apple can lock down the add on market with their peripherals (software media player, online media store, "mp3" player designed for AAC files, etc.)
I think the division in their marketing is interesting, but then again, I love the fine arts of propaganda.