WHAT HAPPENED AT THE NONDESCRIPT ROADSIDE motel outside Oklahoma City was just a fleeting encounter during the twisted cross-country odyssey of the terrorists who would carry out the September 11 attacks. Mohamed Atta, alleged leader of the plot, and two companions wanted to rent a room, but couldn't get the deal they wanted, so they left. It was an incident of no particular importance, except for one thing. The owner of the motel remembers Atta being in the company of Zacarias Moussaoui, the so-called "20th hijacker," who was arrested prior to September 11 and now faces conspiracy charges in connection...