Seahawk - my Daughter (9yo) has a MacBook that I got her a bit over a year ago; she's an ace on it. She's rough on the machine and it has survived and has not required any service. She does her own software updates and gets around the file system very well. She can also make a slideshow, movie and even create songs on Garage Band and has her own website created on iWeb.
Her school is also all Mac, so the choice was even easier for us.
On the superficial side, none of her friends get excited when someone gets a new PC (Windows).
Best,
Kurt