You are looking at this the wrong way. The reason a lot of people buy into iPod/iTunes if the cool/hip apple brand. The slim price diff between apple and competitors "iPods" is apparently not a barrier. The first iPod buyers had to get it going.
For the mac, the first hip/cool is there, and we are all the early adopters. Apple will simply ship a awesome little box (don't expect this to look like any computer you have ever seen before - I'm hoping for an iBook without a screen and battery - a little white ice-block the size of a bestselling novel - that will spawn an after-market just like the iPod), with a slim price diff to a wintel -- marketed as an itunes computer (remember -- this is an iPod add-on!) and watch them fly off the shelves. It's gonna happen - apple has done there homework on this one. I want one real bad!
The Downside of a $500 Dollar Mac