OpenOffice 2.0 was released recently. It has everything that Microsoft Office has plus a few nice extras. Everything means it has a word processor, spreadsheet, presentation program and a database program. A few nice extras come in the shape of saving to PDF and saving presentations to flash.
Yes, that's right and it's lots of fun! You can make flash presentations for your website right from "openoffice impress" which is a lot like microsoft powerpoint. You can upload those flash files to your website and really jazz things up with very little effort.
OpenOffice used to be StarOffice from Sun Microsystems until Sun decided to open source its office programs probably because it couldn't compete with Microsoft and was loosing money trying to keep staroffice alive. So it released staroffice as open source and that was in 2000. Since then a lot has changed and compares favorably with microsoft office.
It also opens and saves files in all microsoft formats so if you still have a lot of office documents, you can still work with them.
Openoffice is a free download from Openoffice.org