Windows 7 has been the most fast selling operating system the the history of Microsoft so far. The software giant has released its fourth quarter earnings after the US market close.

Microsoft has reported profits of $4.52bn (£2.96bn) with an increase of 48 percent on last year, and much of it owing to the success of Windows 7.

In response, shares on Wall Street’s Dow Jones Industrial Average ended the day up nearly 2%.

Despite the great results, there’s still a great deal of pressure on CEO Steve Ballmer, as the rivals Apple imposes a major threat due to Microsoft not being able to capitalise on the growing Mobile Phone OS market.