The government's Intelligence Assessment Department is a very small federal agency with very large computers, located in Sterling, Virginia. The IAD's purpose is to maintain files of names, faces, physical attributes and personal preferences of national security threats and to analyze data about all of the above. If anybody's ever wondered why the CIA or the military can be so certain that one bearded thirty-year-old on the streets of Kabul is an innocent businessman and, to our Western eyes, an identical one a block away is an al Qaeda operative, IAD is the reason. However,