Always helps to know the version!
2007
Animation Tab > set slide transition to auto after xx seconds
Slide Show Tab > Set Up Show check "Loop continuously until esc"
Earlier versions are similar but you will have to search a little in the
slide show menu

Signature
Amazing PPT Hints, Tips and Tutorials
http://www.PPTAlchemy.co.uk
http://www.technologytrish.co.uk
email john AT technologytrish.co.uk
> I will be presenting "passively" next week, and want my powerpoint to run
> continuously in the background. How do I set it up to do a continuous loop
> with each slide showing for 5 to 7 seconds?