The .NET frameworks provides a set of classes that let you work with the Registry, so it is quite easy to create routine that looks for specific keys to determine whether a program is installed or not. For example, the following code checks whether Microsoft Word is installed on the local computer:

' this code assumes that you have used this Imports statement' Imports Microsoft.Win32' Define the RegistryKey objects for the registry hives.Dim regClasses As RegistryKey = Registry.ClassesRoot' Check whether Microsoft Word is installed on this computer,' by searching the HKEY_CLASSES_ROOTWord.Application key.Dim regWord As RegistryKey = regClasses.OpenSubKey("Word.Application")If regWord Is Nothing Then    Console.WriteLine("Microsoft Word isn't installed")Else    Console.WriteLine("Microsoft Word is installed")End If' Always close Registry keys after using them.regWord.Close