PowerPoint 2000 and 2002 share the same file format so files done in 2002
should open in 2000 without doing anything special. However, 2002 has some
new features (particularly animations) that will not play in 2000. If you
are creating files in 2002 to be viewed by people using 2000, you might turn
off the new features. Go to the Tools menu and choose Options. Click on the
Edit tab and click the check boxes in the section under Disable New Features.
If you are trying to view files created in 2002, and they are not working
properly, you might download the PowerPoint 2003 viewer, which supports the
new animations (but doesn't support some other features, such as macros).
--David
David M.Marcovitz
Author of _Powerful PowerPoint for Educators_
http://www.loyola.edu/education/PowerfulPowerPoint/