OpenProj is a free, open source desktop alternative to Microsoft Project. The OpenProj solution is ideal for desktop project management and is available on Linux, Unix, Mac or Windows. OpenProj is a complete desktop replacement of Microsoft Project and even opens existing native Project files. OpenProj shares the most advanced scheduling engine in the industry with Projects On Demand. The OpenProj solution has Gantt Charts, Network Diagrams (PERT Charts), WBS and RBS charts, Earned Value costing and more. You can get more detailed information on OpenProj or download now!
OpenProj is bundled with StarOffice 8.0 that is distributed in Europe, see http://www2.projity.com/partners
If you want to start easily, after download and running, see http://openproj.org/wiki/index.php?title=Spreadsheet