Seems pointless buying a MacBook Air and then not to use OSX?
I read one pays around £250-£300 extra to have OSX on a machine...
Toshiba, HP and Sony have such machines that are as slim, or borderline, and are £200 or so cheaper...
How about Dell and there thin xps 13", its not a great deal bigger,
I know its naughty, but here is a link to an MSN article on thin laptops...
The Thin Laptop Wars - Tech and Gadget Features | Articles – MSN Tech and Gadgets UK
Not a self promo link, so cant see the harm