Microsoft has sold nearly 40 million copies of Vista, its new operating system replacing Windows XP.
According to chairman Bill Gates, sales had been quicker than Microsoft had expected. Windows is used on more than 90% of the world's personal computers.
Vista has been on sale to consumers since 30 January, and there had been concerns that take up might be slow, hurting profits.
"I'm really thrilled at how this has come together," Mr Gates said.
Speaking at a company conference in Los Angeles, he added that one of the reasons for the strong sales was that many consumers were looking to increase the amount of digital media they used, a central feature of the Vista package.....
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