LibreOffice is a complete open source alternative to Microsoft Office. It includes, Writer (word processing), Calc (spreadsheets), Impress (presentations), Base (databases), Math (formula editing), and Draw. Draw is an alternative to Microsoft Publisher for creating multi-page layouts. Open, edit, and create many different file formats including .PUB, .PDF, .DOC, .DOCX, and many more!
Looking for a lightweight alternative to Outlook? Consider this free customizable email client! Opera mail makes reading, labeling, and filtering messages easy, and is compatible with Windows, Mac, and Linux operating systems!
Open Office has become the free standard for Office software. With a familiar layout and feel, Open Office provides a quality, free alternative to Microsoft Office. Open Office will also open, edit, and save in file formats compatible with MS Office!
More details from the OpenOffice.org website are listed below:
Screenshots below from OpenOffice.org
If you need an office suite capable of producing, editing, and viewing Microsoft Office files, Kingsoft Office may be just what you are looking for. Their free version has the equivalent of Word, Excel, and PowerPoint, and all with a similar feel and layout to their expensive counterpart.
Believe it or not, most commercially available software has a FREE twin! (Or at least distant cousin!)