Some had tipped Tami Reller, head of finance at Microsoft's Windows division, to replace Mr Klein.

BBC: Amy Hood

Tami Reller will lead business and marketing strategy for Windows including Surface and partner devices.

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Tami Reller, the new Windows head, stated that Microsoft sold approximately 40 million Windows 8 licenses in the first month, and we will be closely watching the impact on revenues from these sales.

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