Phil,
Your best bet is to open the multi page TIFF file in an application that
supports multi page tiffs.
Then save each page as a single TIF / or PNG or JPG etc
Then insert each page into powerpoint
or take the easy route...
BATCH IMPORT images into PowerPoint
http://www.rdpslides.com/pptfaq/FAQ00050.htm
Cheers
TAJ Simmons
microsoft powerpoint mvp
awesome - powerpoint backgrounds,
http://www.powerpointbackgrounds.com
free powerpoint templates, tutorials, hints and tips etc