I think there is something getting missed here. When you buy a Mac, you are buying a computer console. The software is made for the hardware. You can't make the hardware a separate issue from the software because they are intrinsically linked. If you are going to make that distinction, I want to see a MacBook Air completely wiped with Windows on it, and see if it still has the same performance.
What I like about the AIR is that I can have both operating systems. (I think, I know you can on a MacBook Pro) which means I don't have to decide between the two.
What people seem to be forgetting is that the mac book air and pro prevents upgrading.........you can buy a windows PC / Laptop and easily upgrade it with additional ram, storage, CPU without having to worry about it being soldered to the motherboard.
If you're really looking at costs, you should look at total costs which should include OS upgrades too. MS windows 7 was $199, $399, $429 (depending on version) as an upgrade - I guess win 8 & 9 etc will be similar. OSX mountain lion is $21. Break this down over three years and windows notebooks are really expensive.
Not true. You can upgrade the RAM and storage on the MacBook Pro (not sure about the new Retina model, though).