I don't own either of these laptops, except I know people *love* their macs and I've also heard good things about the VAIO. We actually talked about this a while back here.
I think the choice boils down to whether or not you want an Apple computer running Mac OSX or Windows. What kind of applications will you be using primarily? And for what purpose specifically?
The new Macs have and Intel chip that allows you to run Windows XP and Mac OSX on it, if you're a little technically inclined to set it up.
Apple in general does a great job with their product design, and I'm sure you would love it. On the other hand, if you want to save a bit of cash and you primarily want to run Windows, I would say go for the VAIO.