From:
http://en.wikipedia.org/wiki/OpenOffice.org
OpenOffice.org is a collection of applications that work together closely to provide the features expected from a modern office suite. Many of the components are designed to mirror those available in Microsoft Office.
OpenOffice.org is based on StarOffice, an office suite developed by StarDivision and acquired by Sun Microsystems in August 1999. The source code of the suite was released in July 2000 with the aim of reducing the dominant market share of Microsoft Office by providing a free, open and high-quality alternative. OpenOffice.org is free software, available under the GNU Lesser General Public License (LGPL).
Get it here:
http://download.openoffice.org/2.2.0/