IE9 final will need a little bit of Windows 7 SP1.
Internet Exporer 9 beta hit the public during the middle of this month, which showed off the new browser's tight integration with Windows 7's newest features.
Last week, a TechNet FAQ stated that Windows 7 Service Pack 1 would be required for the install and operation for the final version of Internet Explorer 9, but that was in error.
Microsoft has updated its FAQ to clarify that, while IE9 does use new OS features that aren't available in the RTM build of Windows 7, the SP1 won't be required. Instead, IE9 will install additional system components that are part of SP1 into the Windows 7 RTM.
From the FAQ:
When Microsoft releases Internet Explorer 9, will it require Windows 7 Service Pack 1?
No. Internet Explorer 9 will install on systems that have either Windows 7 RTM or Windows 7 with Service Pack 1 (SP1) installed. When you install Internet Explorer 9 on a system that has Windows 7 RTM installed, additional operating system components are included as part of the installation of Internet Explorer 9. When you install Internet Explorer 9 on a system that has Windows 7 SP1 installed, these additional components are already present with Windows 7 SP1, and do not need to be reinstalled when you install Internet Explorer 9. For this reason, a system reboot is not required when you install Internet Explorer 9 on a system that has Windows 7 SP1 installed.