Managing the File Open with context Menu

If you wish to control or lockdown the "Open With" list that a users sees in their explorer view when the right click documents then you need to manipulate the following registry key area

HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\Explorer\FileExts

Under each file extension their will be a OpenWithList
eg. (.DOC)

You can add new Association or remove existing ones.