There are a ton of discussions in the MBA forum about how much RAM should one buy to run OSX now and in the future, and many people will cite how much RAM OSX consumes on their 4GB or 8GB laptops. I just wanted to mention as somebody who is running OSX with 16GB of RAM that OSX will happily consume over 8GB of that sitting idle, and will get up to 13GB with maybe 10 tabs open in a web browser. It wouldn't surprise me if OSX idled at even higher RAM usage if I had 32GB or 64GB. It's my understanding based on this that OSX will try to use as much RAM as you can give it to page as much data as it can from the hard drive to the RAM. I say this not to claim that you need more than 4 or 8GB to have a pleasant experience with OSX, but only to state that there's a whole world of potential RAM usage that I don't think the MBA community is aware is possible.