Sub AutomatePowerPoint()
    ' This requires that you set a reference to PowerPoint in Tools, References
    ' You could later change these to As Object to avoid that necessity
    Dim oPPTApp As PowerPoint.Application   
    Dim oPPTPres As PowerPoint.Presentation
    Dim sPresentationFile as String

    sPresentationFile = "C:\MyFiles\Somefile.PPT"

    ' Get a reference to PowerPoint app
    Set oPPTApp = New PowerPoint.Application
    '  set it visible or you may get errors - there are ways around this but they're
   '  beyond the scope of this FAQ
    oPPTApp.Visible = True
    ' minimize if you want to hide it:
    ' oPPTApp.WindowState = ppWindowMinimized

    ' Open our source PPT file, get a reference to it
    Set oPPTPres = oPPTApp.Presentations.Open(sPresentationFile)

    With oPPTPres     ' Do stuff ...
      ' Show the number of slides in the file, for example  
      msgbox .Slides.Count           
    End With

    ' Cleanup
    ' Close the presentation
    ' Quit PPT
    ' Release variables
    Set oPPTPres = Nothing
    Set oPPTApp = Nothing

End Sub