title: Retrieving the Version of the Excel Library Programmatically
body: <p>Is there a way to programatically retrieve the version of the Excel Interop Libraries being utilized with C#?  </p>
  
  <p>I know I could probably look in the registry to figure out the installed instance of Microsoft Office, but I was curious if the Excel Libraries contain this information.</p>
  
  <p>I know this information is contained in Visual Studio when you reference the library, but I can't see that information at runtime.  </p>
  
  <p>I am asking this because it dictates the file extension when you save the workbook, and if you save a 2007 workbook with '.xls', 2007 complains about the extension being incorrect.</p>