While looking into Microsoft's Web Client Software Factory (WCSF) I ran into an odd error installing the Guidance Automation Toolkit on Windows Vista.  The error in question was pretty generic but a quick search found a solution.  



Basically, the GuidanceAutomationToolkit.msi needed to be run as an administrator but you cannot right click an msi and simply select "Run as Administrator".  

The work around is simple:
Create a .cmd file
    install_Gat.cmd
Add a command to execute the .msi in question, and
    msiexec /i fully qualified path the the GuidanceAutomationToolkit.msi file
Run the command file as an administrator.
    save the file, then right click and select "Run as Administrator"