LibreOffice is an all-in-one professional office productivity and management package for your PC.
In the same vein as other open source productivity suites like OpenOffice.org, LibreOffice boasts a comprehensive set of office management tools arguably on par with Microsoft Office itself. LibreOffice offers six different office management tools to meet your project management needs: Text Document, Spreadsheet, Presentation, Drawing, Database, and Formula.
Text Document is relatively synonymous with Microsoft Word, where Spreadsheet is like Excel. Presentation mirrors Microsoft's PowerPoint, and Database is similar to Access. Then you also have two additional programs in Drawing and Formula, which are an added bonus to the entire package. LibreOffice is compatible with Microsoft Office's document formats and also supports PDFs natively. It also has its own document format called Open Document.
Unfortunately, if you're unfamiliar with Microsoft Office products, this program might take a little additional time to get used to, particularly if you want to master some of its more advanced features. Regular Microsoft Office users will find LibreOffice's interface quite similar, however, and should pick up on how to use its various programs without too much difficulty.
A great alternative to Microsoft Office, LibreOffice is a must-try for managing your various office projects.