** This is a suggested workaround to install XNA Games Studio on a Vista Machine. Please note that this workaround is only a recommendation and is not officially supported by Microsoft. **
1. Install Visual C# Express 2005.
2. Install XNA Games Studio Express.
3. Install Visual Studio Express Editions 2005 Service Pack 1
4. Install the Visual Studio 2005 Service Pack 1 Update for Windows Vista Beta
5. Most important part: Hit the start menu and type to bring up the icon for the command prompt, Right click the icon and select “Run as administrator” (If you don’t do this it won’t work…)
6. From the command line (cmd.exe) window, run the XNA Game Studio Express installer.
Visual Studio on Windows Vista