At the back of the auditorium, a man cupped his hands over his mouth, improvising a megaphone, the better to bellow: ''Iraq is not the problem. Enron is!'' By then, the waiting crowd had already overstuffed Old Snell Hall on the campus of Clarkson University in northern New York. With all 500 seats filled, 100 people wedged themselves onto spare patches of the peeling linoleum floor. Most of the crowd wanted to hear the case against war, and they were exuberant to be hearing it from Scott Ritter, the onetime United Nations arms inspector and now America's most unlikely peacenik....