From an earlier era of this site. Left here for the record.

Tell if Microsoft Office Save As PDF add in is installed

10 Sep 2010

In this VB.Net Tutorial/Code Example I’m going to show you how to check whether the Microsoft Office 2007 Save As PDF addin (available from here) is installed.

Public Shared Function isPDFSaverInstalled() As Boolean
    Dim rtn As Boolean
    Dim key As RegistryKey = Registry.LocalMachine.OpenSubKey("SoftwareMicrosoftWindowsCurrentVersionUninstall{90120000-00B0-0409-0000-0000000FF1CE}")
    rtn = key IsNot Nothing
    key.Close()
    Return rtn
End Function