Project Management Tools?

I have been using GanttProject or MS Projects for scheduling, and Excel for cost tracking for several years now but recently learned of programs such as Primavera that can do Monte Carlo simulations to look at risk analysis type problems. It also looks like it creates some pretty nice charts and tracking tools. Are there any open-source (or reasonably priced) options such as this? I have found an Excel based template that does the simulation part, but doesn't do much for creating an actual Gantt chart or WBS structure.

I can create my own in Excel, but will take time and may not be as polished as a stand alone program.