Because of the regulatory hurdles in Europe, the Windows 7 version going on sale there was originally to have seen Internet Explorer, Microsoft's Web browser, completely removed.

Regulators have been investigating Microsoft since 2007, following two complaints - one by the makers of the Norwegian web browser Opera, and another from the industry group European Committee for Interoperable Systems (ECIS), accusing Microsoft of unfairly obstructing the ability of rival applications to work on its operating systems.

They say the practice of bundling Internet Explorer with Windows puts competitors at an unfair disadvantage.

Meanwhile, the company on Thursday reported fourth quarter net income of $3.05 billion, down from $4.3 billion in the same period last year. Revenue was at $13.1 billion, a 17 per cent drop from the year-ago quarter.

It reported a 29 per cent drop in sales of its Windows software.

In a statement, CFO Chris Liddell said the business "continued to be negatively impacted by weakness in the global PC and server markets."