I like OpenOffice.org, the free, open source workalike for Microsoft Office. (Yes, it’s really called OpenOffice.org, but I just say “Open Office.”) Version 3 was just released and you can download it and install it at no charge.
If you don’t want to pay all that money for Microsoft Office at home, it’s worth using. You can read and write Microsoft Office documents without any trouble. And here at work it’s handy because you can save a Word document, or any other Microsoft Office file, as a PDF.