I was walking through the office with Lenovo's ThinkPad X1 Carbon dangling between two fingers when my colleague spied the logo. "That was my first computer," she said with immeasurable fondness. The ThinkPad was a lot of people's first computer. Early ThinkPads were built like a tank and ran smooth like a spinning top. These days, the brand, which IBM sold to Lenovo a decade ago, doesn't have quite its 90s cachet, but its continues to be a workhorse -- and the new fifth generation of its stellar Carbon line is a slick refinement of everything you've ever loved about that familiar black machine.