According to StatCounter, it's taken roughly two years for Redmond's latest to surpass XP and become the world's most popular operating system. October 2011 marks the first time that Windows 7 has overtaken XP globally, with a 40 percent share of the market versus the latter's 38. As for Vista, it's been holding steady at around 11. Not that it's much of a surprise, as in North America, Windows 7 took the crown back in April of this year. Rounding out the top five, are OS X (though it's not clear whether that captures all of Cupertino's beasts) and Linux, which come in at 7 and 0.82 percent respectively.