The Asus Zenbook UX31 is one of the first laptops to conform to Intel's Ultrabook specification. And, right away, we'll tell you - it stands toe-to-toe with Apple's MacBook Air in the fight for the title of best luxury ultraportable. The 13-inch Zenbook is fantastic to look at. When closed, the wedge-shaped laptop measures 17mm at its thickest point and a mere...