It was going to happen and some point.
Windows XP was launched almost 10 years ago, on August 24, 2001 and is still the world's most popular operating system. Windows Vista failed to become a replacement for XP, but Windows 7 is apparently eating away share from XP at an accelerating pace. However, Windows 7 cannot collect all those users that XP and Windows Vista are losing every month: XP and Vista lost a combined 1.57 points of OS market share in July, while Windows 7 gained just 0.74 points and now stands at 27.87 percent. Windows overall dropped to from 88.29 percent to 87.66 percent market share, while Mac OS X climbed from 5.37 percent to 5.59 percent and iOS is now estimated to hold 2.98 percent.
StatCounter, by the way, estimates Windows XP share at 43.89 percent and Windows 7 share at 36.06 percent.
A decrease in Windows XP market share and an increase in Windows 7 is critical for Microsoft to lay the foundation for greater IE9 and IE10 adoption to promote a new HTML5 app model that will arrive with Windows 8 in 2012.