OpenOffice provides a free alternative for creating and reading Word Documents (.doc files), Excel spreadsheets(.xls files) and PowerPoint Presentations(.ppt files). Note that it has some other modules which are not discussed here. And Note that this product does NOT provide function parallel to the Microsoft Outlook email program contained in the Microsoft Office Suite of programs.
OpenOffice can be downloaded here: http://download.openoffice.org/
The only caveat here is that this Office look-alike suite defaults to its own file formats for output. So you MUST change the default file types for new files or you will NOT be able to create and then send a document to someone else and have them be able read it with MS Office programs, UNLESS you make sure it is saved in the MS format every time you save a file for the first time. In general it probably makes more sense to change the default and then you won't have to worry about output format every time you save a document/spreadsheet/presentation.
To change the defaults is simple. After installation of OpenOffice navigate to:
and change "default file format"s to:
Text Document format : Microsoft Word 97/2000/XP
Spreadsheet format : Microsoft Excel 97/2000/XP
Presentation format : Microsoft Powerpoint 97/2000/XP
Click OK button