title: How do I detect dependencies and abort an install using Visual Studio Setup projct
body: <p>I need to detect 2 conditions before installing and application using an installer created with visual studio 2010. </p>
  
  <p><strong>Detect an existing application</strong></p>
  
  <p>I need to not allow an app to install unless another application is already install. For example if MS Office is not installed on the PC alert the user and abort the install. </p>
  
  <p><strong>Detect an assembly installed in the GAC</strong></p>
  
  <p>I also need to at check to see if an assembly is in the GAC. Checking if a specific version or higher is in the GAC would ideal. </p>
  
  <p>I do not want to include the assembly or install the prerequisite. I just need to verify if it is installed and if not alert the user and abort the install.</p>