OpenOffice is a suite of applications similar to Micrsosoft Office for personal computers. There is a word processing app, a spreadsheet app, a presentation app, and a database app. You can open a Microsoft Office file with the appropriate OpenOffice app and read it, edit it and save it as a Microsoft Office file, or as an OpenOffice file. You can for example, open OpenOffice Impress presentation software, create a slide presentation and save it in the MS Office Powerpoint format, which can be opened by someone using MS Powerpoint. So if you cannot afford to purchase MS Office, you can go to the following link and download OpenOffice:
You can also export your presentation file as a Flash (.swf) file so anyone using IE or Firefox (or any web browser that has a Flash plugin) to view your presentaion on the web browser.
and the greatest thing is that it is FREE, FREE, FREE!!!!!