But Net Applications' data also shows that the newest IE9 rivals -- Chrome 10 and Firefox 4 -- have significant chunks of the Windows 7 browser market. Chrome 10, which Google began pushing to current Chrome users via the browser's silent update mechanism almost a month ago, accounted for 10.2% of Windows 7 browsers in March. Firefox 4, on the other hand, lagged behind IE9 with a 2.8% share on Windows 7.

Ignore the numbers for now, Gavin said earlier this week when he blasted early comparisons as because of the differences in the upgrade mechanisms of IE, Chrome and Firefox.

Microsoft plans to add IE9 to Windows Update sometime this month -- today he declined to set a date -- from where it will be offered to Vista and Windows 7 users. Mozilla has yet to offer Firefox 4 to customers running older versions of its browser, but will do that soon, a spokeswoman said Thursday.

The roll-out of IE9 via Windows Update and its Automatics Updates option will wrap up by the end of June, Gavin said today.

While the numbers may not provide an unambiguous case for the success of any of the newest browsers, one thing is clear: Microsoft has bet on IE9 and won't back away from that bet.