title: VDPROJ auto upgrading vs. uninstall/reinstall
body: <p>I've seen a confusing behavior regarding the MSI files generated by a VDPROJ file.  If I build my MSI in Visual Studio and then right-click and pick "Install" from within Visual Studio, it will automagically uninstall any version that is already installed and then install the new MSI.</p>
  
  <p>However, if take the generated MSI and run it directly it will complain if a previous version is already installed.  I have to uninstall it explicitly (in Add/Remove Programs) first.</p>
  
  <p>What's the deal?  Is there a command-line argument that Visual Studio executes the MSI with?</p>