n01getsout

OpenOffice is a direct competitor of Microsoft Office. It is even mostly compatible with Microsoft Office. It has a word processor, a spreadsheet, a drawing program, a database program, and a presentation program. It has many advanced features, like wizards to guide you, spellchecker, autocorrect, and it can save documents as PDF files. And it's free.

How to switch from Microsoft Office to Open Office
Sharing files between OO.o and MS Office
Also try LanguageTool, an open source grammar checker for OpenOffice.org