The 100 millionth installation was logged on 8 January. Citing data from statistics firm WebSideStory, Microsoft claimed that IE7 currently makes up about 25 per cent of the world's browsers.
This makes IE7 the world's second most prevalent browser, trailing only behind IE6.
"We expect these numbers to rise as we complete our final localised versions and scale up auto-update distribution, and with the consumer availability of Windows Vista on 30 January," wrote Tony Chor, a group programme manager at Microsoft.
Data from other analysts had suggested that Firefox runs on roughly 10 to 12 per cent of the world's desktop computers.
IE7 is automatically distributed as a high priority update to computers through the auto-update feature built into Windows. Users are prompted about the update before it is installed.
Enterprise users are expected to delay rolling out the software because it can cause compatibility issues with internally developed software.
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