Microsoft unveils 'Surface' with keyboard cover

Each tablet comes with a Laptop Keyboard Cover that is just 3 millimeters thick. The kickstand for both tablets was just 0.7 millimeters thick, less than the thickness of a credit card.

Microsoft has been making software for tablets since 2002, when it shipped the Windows XP Tablet PC Edition. Many big PC makers produced tablets that ran the software, but they were never big sellers. The tablets were based on PC technology, and were heavy, with short battery lives.

Microsoft didn't say how long the Surface would last on battery power.

Microsoft's decision to make its own tablet is a departure from the software maker's strategy the personal computer market. With PCs, Microsoft was content to leave the design and marketing of the hardware to other companies, such as Hewlett-Packard, Dell, Lenovo and Acer, that licensed the Windows operating system and other software applications.

The more hands-on approach with its tablet indicates that Microsoft either lacks confidence in the ability of its PC partners to design compelling alternatives to Apple's iPad or it believes it needs more control to ensure Windows plays a major role in the increasingly important mobile computing market.

Whatever Microsoft's Laptop Keyboard is , the company's tablet plans risk alienating some of its longtime partners in the PC industry