So I'm finally going to get an MBA. I was set on the 11" for maximum portability but after going to the Apple store and spending some time with them I've decided the 13" will suite my eyes much better. I just love the form factor of the 11" but I think in the end I'd be unhappy and going with the 13" will give me an excuse to get the 11" at some point. My question is this. Does the 13" have a built in fan? If so, is it noisy? A quiet fan is very important to me. I will be getting 8GB RAM and 2.0GHz Processor. As always, your help is appreciated.