OpenOffice includes Impress, a free presentation design package. Slideshows can be saved in a format recognised by Microsoft Office 2003/2007, also.

http://openoffice.org/

If you insist on using Office, Microsoft has a full featured 60-day Microsoft Office 2007 trial, take a look at http://us20.trymicrosoftoffice.com/default.aspx

If you just need to read/view PowerPoint files, and not create or edit them, then download the free Microsoft PowerPoint Viewer from

http://www.microsoft.com/downloads/d...displaylang=en (PowerPoint 2003)

http://www.microsoft.com/downloads/d...displaylang=en (PowerPoint 2007)