Set Variable MSI31 to TRUE
Check/Install Windows Installer (check v3.1, get result into variable MSI31)
if Variable MSI31 Equals FALSE
  Get System Setting Windows NT Kernel (NT4, 2000, XP, 2003, Vista, 2008, 7, 2008 R2, 8, Server 8) into ISNT
  if Variable ISNT Equals TRUE
    Comment: Windows Installer 3.1 has specific requirements on NT kernels
    Get System Setting Windows 2000 into IS2000
    if Variable IS2000 Equals FALSE
      Comment: At least Windows 2000 is required
      MessageBox: $TITLE$ Setup, $TITLE$ requires at least Windows 2000 or later. Please upgrade your operating system and try again.$NEWLINE$$NEWLINE$$TITLE$ Setup cannot continue.
      Terminate Installation
    end
    Get System Setting Windows XP into ISXP
    if Variable ISXP Equals FALSE
      Comment: For Windows 2000, at least Service Pack 3 is required
      Get System Setting Service Pack 3 into ISSP3
      if Variable ISSP3 Equals FALSE
        MessageBox: $TITLE$ Setup, $TITLE$ requires at least Service Pack 3 or later. Please upgrade your operating system and try again.$NEWLINE$$NEWLINE$$TITLE$ Setup cannot continue.
        Terminate Installation
      end
    end
  end
  Set Variable PREREQ to TRUE
  Set Variable PRELIST to $PRELIST$$NEWLINE$Microsoft Windows Installer 3.1
end
 
