Apple today announced that it has sold more than 2 million copies of Mac OS X Leopard in first 48 hours of its release. Leopard was released at 6pm on Friday and Apple had estimated that around 20-25 million computers sold by Apple could be upgraded to the new operating system. Microsoft has an install base of about 800 million and according Netapplications by end of September 2007 Windows Vista had 7.38% of OS market share. It took Mac OS X Leopard just two days to achieve what Windows Vista has not achieved after 10 months. These numbers definitely show Mac’s very strong brand loyalty and Mac users strong belief in quality of new product released by Apple.