We all know that the design of the IBM ThinkPad which became popular in the 90s has been retained by Lenovo in current models. To many, this design already feels quite old.  While ThinkPads are tough and sturdy Lenovo has lost many would-be buyers because of its design. And just when we thought that the ThinkPad can never go sexy, Lenovo creates the ThinkPad X1, an ultrathin notebook that could compete with Samsung Series 9 and Apple MacBook Air in thinness.  The Thinkpad X1 measures just 16.5mm on its thinnest part and 21.5mm on its thickest.  This is definitely the thinnest Thinkpad to date. The ThinkPad X1 has shown up online sporting a 2.5GHz Core i5-2520M processor, a 160GB SSD, a 13.3-inch Gorilla Glass screen. It has an 8GB DDR3 RAM, an SDXC card reader, a 1366 x 768 resolution and a LED backlit keyboard. Here are the essential features and specs of Lenovo ThinkPad X1. Dimensions (width x…