The Atheism Tapes

Probably the best documentary (mini series) that you can find on the topic. I specifically remember liking it because it had such wonderful discussion where the theists were actually well educated people who believed in things like evolution and rejected creationism. I recall the Dawkins discussion with a philosopher and (as an atheist) I feel the other guy actually 'won' that round. It's a lot more cohesive to the topic than most other documentaries of the same subject.