SEATTLE: Microsoft Corp Chief Executive Steve Ballmer touted new tablet-style Windows devices from more than a dozen manufacturers at a conference, underlining the giant software company's eagerness to counter the explosion of interest in Apple Inc's iPad. New tablet or slate devices -- small, hand-held, wireless computers -- running Microsoft's Windows 7 operating system are in the pipeline from Acer Inc, Dell Inc, Samsung Electronics Co Ltd, Toshiba Corp, Sony Corp and several other PC makers, Ballmer said at the company's annual partner conference in Washington, DC, which was webcast. "This year, one of the most important things that we will do in the smart device category is really push forward with Windows 7-based slates," said Ballmer. "This is a terribly important area for us." Apple's iPad, launched in April, has already sold more than 2 million units worldwide, and threatens to take customers away from Microsoft-dominated desktop computing. A notable exception to Ballmer's list was Hewlett-Packard Co, which has said it plans to build slate devices running the operating system devised by Palm Inc, which HP bought this year.