Nowadays, there really is no need to pay for Microsoft Office if all you need to do is basic editing of documents, spreadsheets and presentations.
Whenever people ask me what I can recommend as a free alternative to Microsoft Office, I'll frequently recommend OpenOffice.org. OpenOffice.org is a multi-platform and multilingual office suite that is compatible with all other major office suites (meaning it will open and edit Word, Powerpoint documents etc) and best of all, its absolutely free to use.
OpenOffice.org includes the key desktop applications, such as a word processor, spreadsheet, presentation manager, and drawing program with a user interface and feature set similar to other office suites. OpenOffice.org may not be quite as polished as Microsoft Office but considering you get all this for nothing, you really can't complain. The six components OpenOffice.org comes with are Write, Calc (spreadsheets), Impress (presentations), Draw, Base (database management) and Formula (mathematical application).
There are some drawbacks to OpenOffice.org of course. Occasionally, you will experience formatting or printing issues when using documents that have been made in Microsoft Office. However, the main one is that since it is largely based on Java, it can be rather slow and unresponsive particularly when opening new files. This has certainly been improved in the latest releases but its still a sluggish old thing compared to Microsoft Office. The numerous settings and buttons that come with OpenOffice.org can be a little overwhelming too and it would be nice to see it made a little simpler and streamlined in future releases.
If you're strapped for cash or simply don't want to pollute your Mac with Microsoft software, OpenOffice.org is an excellent, if slightly imperfect alternative.
