A used 11" macbook air also fits your requirements. It runs windows or linux just as well as mac os x http://www.ebay.com/itm/Apple-MacBook-Air-11-120GB-Flash-

A used 11" macbook air also fits your requirements. It runs windows or linux just as well as mac os x http://www.ebay.com/itm/Apple-MacBook-Air-11-120GB-Flash-4GB-RAM-1-6-GHz-Intel-Core-2-Duo-Late-2010-/181201945728?pt=Apple_Laptops&hash=item2a307a4480 http://www.ebay.com/itm/Apple-MacBook-Air-11-120GB-Flash-4GB...