Air+unibody, both suck!
Stupidly, I have a first generation, basic model MacBook Air and a first generation unibody MacBook with 2.4 GHz. I will NEVER, EVER, EVER buy a first generation Apple product EVER again.
CPU whine, overheating, constant fan noise on both, misaligned keys on the MB...
I use the Air for typing as it has a nice screen and I use the MB, when I need to do anything power- or graphics hungry. But not in the garden. Or in sunlight. Or when the lights are on. And not anything involving Firewire.
Stupid Apple!