How do we install Internet Explorer 9 side by side with Internet Explorer 8 for evaluation?
Running multiple versions of Internet Explorer on a single instance of Windows is an unsupported solution. For example, organizations cannot install Internet Explorer 6 and Internet Explorer 8 side by side on a single operating system. To run two versions of Internet Explorer side by side, we recommend that organizations use virtualization technologies such as Microsoft® Enterprise Desktop Virtualization (MED-V), a feature of the Microsoft Desktop Optimization Pack, or Remote Desktop Services. You can also use Windows XP Mode to test application compatibility in Internet Explorer 9 against Internet Explorer 6. Windows XP Mode with Virtual PC, available on Windows 7 Professional and Windows 7 Ultimate, allows you to run multiple Windows environments and multiple versions of Internet Explorer simultaneously. For more information, or to download, see Windows XP Mode with Virtual PC.