In its biggest-ever push into the hardware business, Microsoft on Monday unveiled a tablet computer called Surface that is designed to challenge Apple’s iPad. At an event here, the company showed off the device, which is about the same weight and thickness as an iPad, with a 10.6-inch screen. The tablet has a built-in “kickstand” that will allow users to prop it up for watching movies, and a detachable cover that will serve double duty as a keyboard. The Surface tablet will run a variation of Windows 8, a forthcoming version of Microsoft’s flagship operating system. Steve Ballmer, Microsoft’s chief executive, said the product was part of a long-running effort by Microsoft to create hardware, like computer mice, that show off innovations in its software. Read the full story at The New York Times.