first of all you must import namespace [ microsoft.win32] to access the registery classes in .net framwork

then this code will check the regestery if the application is installed or not

VB Code:
  1. Dim TargetKey As RegistryKey
  2.         TargetKey = Registry.ClassesRoot.OpenSubKey("word.application")
  3.         If TargetKey Is Nothing Then
  4.             MsgBox("Word application is not found")
  5.         Else    'key is found
  6.             MsgBox("Word application is found")
  7.             TargetKey.Close()
  8.         End If

you can change the string in the second line from "word.application" to "excel.application" or "access.application" in order to check for different components.

rgds