The pre-Release Candidate Partner Build of Internet Explorer 8 fails to play nice with the first fully-fledged Beta development milestone of Windows 7. This behavior was, of course, to be expected, as Windows 7 comes with its own Build of IE8 as a default component of the operating system. At the same time, Internet Explorer 8 Partner Build is only meant to integrate with Windows XP Service Pack 2 and SP3, Windows Vista RTM and SP1, Windows Server 2003 SP2 and Windows Server 2008 RTM/SP1.

In mid-December 2008, Microsoft made available the Partner Build of IE8, a post Beta 2 version, but a pre-Release Candidate development milestone, at least a pre-public RC, as the Build information did recommend the bits as Release Candidate 1 of Internet Explorer 8.

At that time, I contacted the company and asked whether the RC and RTW (release to web) Builds of Internet Explorer 8 would be offered for Windows 7 Beta, RC and RTM (released to manufacturing). This is all that a Microsoft spokesperson had to say on the matter: “The release of Internet Explorer 8 is not dependent on any future release of Windows.”

As you can very well see from the adjacent images, while IE8 (RC1) Partner Build installs and runs perfectly on Windows Vista, the same cannot be said about Windows 8. In fact, the message returned by Windows 7 Beta 1 Build 7000 is downright ridiculous: “Internet Explorer 8 is not supported on this operating system.”

Just to make things clear, a separate Beta build of Internet Explorer 8, version 8.0.7000.0, is shipped as a default component of Windows 7 Beta 1, and does run on the operating system. What is not supported is the IE8 variant meant for integration with Windows Vista. By comparison, IE8 Beta 2 for Windows Vista is version 8.0.6001.18241, while IE8 (RC1) Partner Build for Vista is 8.0.6001.18343.

Both IE8 Partner Build and Windows 7 Beta 1 are available only to a select pool of Microsoft testers. However, software products have been leaked and are available for download from third-party sources including BitTorrent websites. Microsoft has confirmed officially that in early 2009 it will deliver Internet Explorer 8 Release Candidate 1 and Windows 7 Beta 1.

Internet Explorer 8 (IE8) Beta 2 is available for download here.