It is possible but not simple!
You will need to make a mask in photoshop for the best effect and move it
over the slide. If you email me I can send you a demo

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email john AT technologytrish.co.uk
John Wilson
Microsoft Certified Office Specialist
http://www.technologytrish.co.uk/ppttipshome.html
> I am doing a powerpoint presentation and am trying to get the slide to be
> black with a spotlight on part of it - hopefully it would travel across the
> page before ending up on the text/ image.