Also, go read this essay by Malcolm Nance at the Small Wars Journal blog:
Waterboarding is Torture… Period
As a former Master Instructor and Chief of Training at the US Navy Survival, Evasion, Resistance and Escape School (SERE) in San Diego, California I know the waterboard personally and intimately. SERE staff were required undergo the waterboard at its fullest. I was no exception. I have personally led, witnessed and supervised waterboarding of hundreds of people.