You've gotta be thin to compete with the iPad. The Surface for Windows RT is 9.3 millimeters thick--or "thin," as the marketing folks are fond of saying. That's 0.1 millimeters thinner than the new iPad, not that you'll notice the difference. The Surface's edges are beveled back at 22 degrees, making the slate appear even slimmer than its specs might suggest. Surface is the first PC with a full magnesium case, making it light yet rigid, Redmond says.