I've got both. I prefer the Vista to the Mac to be honest, i just find it easier to use, and i hate having to press control to right click sometimes, pain in the arse.
Although, i like using garage band on the Mac (its a laptop), and the movie editing software is very easy to use. i also use it for watching dvds and just the occaisional internet use (like right now).
Just depends what you want to use it for to be honest, one isnt better than the other, they're too different for that really.
P.S. The fact that you can't go through every window on macs using Apple Button tab really grinds my gears!