One of the most highly annoying *features* of Adobe’s Acrobat 7 product is that it installs itself in all of the Microsoft Office applications whether you want it to or not and there appears to be no easy way to stop it. If you use Adobe Acrobat, Outlook has a Send as PDF button on the toolbar. To remove the button, you need to disable the COM addin.

Go to:

HKEY LOCAL MACHINE
   \Software
      \Microsoft
         \Office
            \Outlook
               \Addins
                  \PDFMOutlook.PDFMOutlook

Change the LoadBehavior value from 3 to 2. Restart Outlook. The PDF functions will still be available in Word and the other Office programs. The same registry key appears to exist for Word, Excel, and Access as well. I haven't figured-out how to remove Acrobat from Visio though.