If you have computers without MS Office and don't want to pay for it, give the latest LibreOffice a look. With a newly designed interface, it's become much easier to navigate and use. When you install, be sure to select 'custom' and check off all document types you want LIbreOffice to automatically open (vs the trial Office your PC probably has).

LibreOffice Updates, Doesn't Look Like Crap Anymore
Windows/Mac/Linux: LibreOffice, has always been powerful enough to stand up against Microsoft Office, but it's also been a bit ugly and clunky to use. Today, they rolled out an update the overhauls the UI and makes it a lot more useable.