OpenProj is an OpenSource free alternative to MS Project.

It provides Gantt Charts, Network Diagrams (PERT Charts), WBS and RBS charts, Earned Value costing and others. I have not used MS Project all that much but the interface seems very similar so I would imagine that even a seasoned MS Project expert would feel comfortable using OpenProj.

OpenProj will read and write native MS Project files so you won’t lose what you have already created.

Originally a commercial product, OpenProj runs on Linux, Unix, Mac or Windows desktops.

Next time I need some more hard-core project planning software, I am going to spend some quality time with this one.