I've never really done any charting or graphing in asp.net, but my current project is going to need some fairly extensive charting, in particular graphs that can be updated dynamicaly by the user, by changing start dates, criteria etc. I'm looking for some suggestions on the best charting tool for doing this.
I'd prefer a free tool, but may have some budget for a paid one. Will be using asp.net MVC written in C#.