Aording to the Net Applications' latest data, worldwide, IE9 share on Windows 7 reached 3.6% for the month of March. The combination of IE9 and Windows 7 with the PC creates the best experience for users of the web and the developers and designers that create those sites.
The adoption rate of IE9 is about five times higher then what we saw for Internet Explorer 8 in the same time frame.
Microsoft seems willing to sacrifice usage share in the short term in order to leapfrog the competition in the long run by applying all their resources to modern versions of Windows. Although Windows XP currently has 54% of global usage share, Windows 7 usage share is following a strong, fairly linear path upwards and Windows versions from Vista forward should have a majority share within a couple years.