Despite heavy criticism of its Windows Vista operating system, Microsoft has reported that strong sales of the OS helped the company report impressive revenue in its most recent financial quarter.

According to its fiscal 2008 second quarter, Microsoft's client business achieved $4.34bn in revenue compared to $2.59bn a year ago. According to Microsoft, its client business has grown 20 percent on average since Windows Vista was made available nearly a year ago, and the company believes Vista began hitting its stride for adoption in the second quarter. According to Microsoft, it has sold more than 100 million licences for Vista.

Vista sales helped Microsoft beat Wall Street expectations for both revenue and earnings per share during the quarter. Strong performance for Office 2007, as well as Exchange and SharePoint server software, also aided the growth.

Microsoft reported total revenue of $16.37bn for the quarter which ended on December 31, an increase of 30 percent year on year and a number that solidly beat the $15.95bn that Thomson Financial analysts had estimated. Last year for the same period Microsoft reported $12.54bn in revenue.

The company said 60 percent of its revenue came from outside the US, adding that emerging markets are becoming increasingly important. In the past several years, Microsoft has made significant investments in selling its technology in developing countries such as India, Brazil and China.