Microsoft shipped over 20 million copies of its new Windows Vista OS in the first month from its general availability at the end of January.
Microsoft said this figure was more than double the initial rate of sales for its previous OS Windows XP.
In January 2002, the company announced sales of Windows XP licenses had exceeded 17 million after two months on the market.
The 20million-plus Vista sales shipped represent Vista licenses sold to PC manufacturers, copies of upgrades and the full packaged product sold to retailers.
The figure also includes copies ordered through the Windows Vista Express Upgrade programme from 30 January to 28 February 2007.
Related article: Vista will have no impact on PC shipments
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