I tried to install Virtual PC 2007 in Win 7 beta and the installer crashed. I followed this instruction from the Win 7 Action Center. And that did it.
An issue with the Customer Experience Improvement Program (CEIP) client in Windows 7 beta is causing Explorer and some MSI-based installers to stop working properly.
To solve this problem, follow these steps:
Click the Start button , click All Programs, and then click Accessories.
Right-click Command Prompt, and then click Run as administrator. In the User Account Control window, verify that Program name is Windows Command Processor, and then click Yes.
In the Administrator: Command Prompt window, type or paste the following text at the prompt:
reg delete HKLM\SOFTWARE\Microsoft\SQMClient\Windows\DisabledSessions /va /f
Press Enter to install the solution.
If The operation completed successfully displays, close the Administrator: Command Prompt window to complete this procedure. If "ERROR: Access is denied" displays, repeat this procedure from the top, making sure you clicked Run as administrator in step two.