The final version of Microsoft's latest web browser, Internet Explorer 9 (IE9), will require Windows 7 Service Pack 1 (SP1), a not-yet-released major update to the operating system, the software company confirmed.
The Ars Technica technology site first reported on the Windows 7 SP1 requirement Thursday.
Microsoft has not divulged the release dates of Windows 7 SP1 or IE9, but both are expected to appear in the first half of 2011. That six-month window covers Microsoft's current plans for Windows 7 SP1, while many experts believe the company will ship the final of IE9 in April 2011 to coincide with its annual MIX conference.
The FAQ suggests that the final versions of both two products will ship simultaneously, or nearly so.
The beta of IE9 that launched on September 15 requires four already-available Windows 7 updates - two published in June, the others in August - that are primarily graphics-related bug fixes or that add support for IE9 functionality.
But the final will apparently demand more, a curious move since Microsoft has repeatedly characterised Windows 7 SP1 as nothing more than a collection of previously-released security patches and other fixes. Unlike 2004's Windows XP SP2, Windows 7 SP1 will not include new features.
"Organisations must plan, pilot and deploy Internet Explorer 9 as part of or after a Windows 7 SP1 deployment," Microsoft maintained in the FAQ.
The SP1 requirement may be derived from the four updates already available - they would be packaged in SP1 - or from future, not-yet-released updates - or a combination of the two.
This isn't the first time Microsoft has blocked some users from running IE9. The new browser will not run on Windows XP , the still-dominant nine-year-old OS.
Earlier this week, Microsoft urged companies not to wait for IE9 to migrate their PCs to Windows 7, a recommendation the FAQ repeated. "Microsoft recommends that organisations do not disrupt ongoing deployment projects but continue deploying Windows 7 and Internet Explorer 8," the FAQ stated.
Pushing enterprises to upgrade to Windows 7 now, not at some point after IE9's launch, is to Microsoft's benefit, of course, since the sooner it gets customers onto the new operating system, the sooner it reaps revenue from the OS and associated products, such as Windows Server 2008 R2 and SharePoint 2010.
Microsoft made a point to stress that even though companies moving to the Windows 7/IE8 combination may use that browser for only a limited time, the work would not be wasted.
"Your Internet Explorer 8 migration investments will be preserved when you are ready to deploy Internet Explorer 9," argued Rich Reynolds , Microsoft's chief Windows marketing executive, in a blog.
Even so, Microsoft doesn't want to dissuade users from trying out IE9.
"Regardless of your organisation's stage of Windows 7 deployment plans, we still encourage you to explore the Internet Explorer 9 Beta," added Reynolds.
The IE9 FAQ also said that Microsoft will release the usual array of deployment tools for IE9, including a blocking utility to prevent Windows Update from automatically downloading and installing the new browser. Microsoft has released such blocking tools for other browsers, including IE8 in 2009 and IE7 in 2006.
Microsoft did not immediately reply to questions on the IE9-Windows 7 SP1 ties, including why SP1 is necessary to run the new browser.
The IE9 beta can be downloaded from Microsoft's dedicated site.
See also: In pictures: Internet Explorer 9