Tip for Visual Studio 2005
Useful tidbit from the MVP summit:
To start from a clean slate with an install of Visual Studio 2005 CTP, open a command prompt, navigate to the Visual Studio install directory, and enter the following command:
devenv /resetuserdata
This will reset user-specific settings, etc. to provide you with a (mostly) clean install without any customizations you may have made. This can be useful for demos, etc.