Kenguru: But you can't make the blanket statement that all free tools are dangerous! Many programs you pay for are also dangerous, believe me, I have experienced it. Many national governments and education institutions are moving towards open source, and getting rid of software they have to keep paying for. That's one of Microsoft's major problems right now.
You can be sure by asking others, looking for reviews, and checking it out before you obtain it, just like any other product.