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“What you’ve seen and heard should leave no doubt that Windows 8 shatters perceptions of what a PC is now,” said Microsoft chief Steve Ballmer.

A screen image of Windows 8.

associated press/MICROSOFT

Windows division chief Steven Sinofsky, left, and Panos Panay, general manager for Surface Computing, introduced the Surface tablet.

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Sinofsky showed a Surface model with skateboard wheels attached to show the device's strength.