Microsoft Corp introduced its own line of tablet computers on Monday at a much-hyped press event in Los Angeles, marking a major strategic shift for the software giant as it struggles to compete with Apple Inc and re-invent its aging Windows franchise.

The new tablet line, named Surface, includes a consumer device aimed directly at the Apple iPad, and another, larger machine designed to compete with lightweight laptops. Both include a keyboard that doubles as a cover, and both will be powered by versions of the new Windows 8 operating system (see graphic).

The move breaks with Microsoft’s operating model of the past 37 years, which has relied on computer manufacturers to make and market machines running Windows. It could throw the world’s largest software company into direct competition with its closest hardware partners such as Samsung Electronics and Hewlett-Packard.

The new software is the biggest overhaul of Windows in years, and features a new touch-friendly interface dubbed “Metro”. It is scheduled to be available for the Christmas shopping season.

Industry watchers were impressed by the devices’ specifications, but doubted they were a sure-fire hit.

“I don’t see this as an iPad killer, but it has a lot of potential,” said Sarah Rotman Epps, an analyst at tech research firm Forrester. Sales of tablets are expected to triple in the next two years.