Microsoft’s CEO Steve Ballmer says that Microsoft has sold over 400 million Windows 7 licences since the product was first launched in October 2009, which is equal to about 7 copies/sec being sold.

Steve Ballmer announced the figure today at the company’s Worldwide Partner Conference 2011.

Brandon LeBlanc, communications manager at Microsoft, later announced the company’s contentment with todays figure announced:

Our previous statement of 7 copies of Windows 7 sold a second continues to hold true. We continue to see excellent momentum for Windows 7

Although Window’s success shouldn’t be surprising as it was continuously supporte d by entusiasts and user alike, but selling 240 million licenses within a year made Windows 7 Microsofts most successful product to date.