On Windows 7, IE9 is the second-most-popular browser, with a 21% share compared to IE8's leading 31.6%. In third and fourth place, respectively, were Firefox 6 and Chrome 13 with 13.9% and 13.1%.

Microsoft has never outlined an alternate strategy for stopping IE defections. While the focus on IE9 may pay off down the road -- perhaps when the huge numbers of Windows XP users finally retire that OS -- it's failed to slow defections. Since IE9's debut, Microsoft has lost 4 percentage points of share.

That was again illustrated last month: At the same time that IE9 gained eight-tenths of a point for a 8.7% share of the browsers running on all operating systems, the other editions collectively sloughed almost twice as much share. IE8, for instance, lost about two-tenths of a point, slipping to 29.9%, while IE7 and IE6 lost two-tenths of a point and 1.1 points, respectively.

IE6, which Microsoft has been trying to kill for more than two years, dropped by 1.1 points, the biggest decline since January 2011. Globally, IE6 -- a decade-old browser introduced just before the launch of Windows XP -- now accounts for an 8.6% share.

"And if you remove China's figures, IE6 only represents 3.5% usage share worldwide," said Capriotti in a Saturday .