I am a big fan of using free software development tools, especially if they are written in Open Source Java. Recently I had some success with GanttProject, a project management tool that supports Gantt charts. The webpage has an animated demo to help you get started. I am happy to report that it did what I needed.
Here is a list of more free and Open Source software development tools that I use: http://www.CroftSoft.com/library/links/