<p>There's not a lot to add to the subject really.</p>

<p>I am after a free task board/ burndown reporting tool for Windows.</p>

Well, without knowing more about your situation, I have to
highly
recommend a wall of index cards and a handdrawn chart on flip chart paper. Works much better than any software in the standard situation.
If you really have to use software, there is none that I could recommend unreservedly, let alone a free one. You might want to keep in mind that some of the commercial ones are free for open source or academic projects, too. Which one's right for you will depend, besides other things, on how much you want it to define your process.