It has been 16 years this month since the first traditional chess match between world champion Garry Kasparov and IBM's Deep Blue supercomputer. In the first challenge, Deep Blue won one game, tied two and lost three. In the rematch the next year, Deep Blue defeated Kasparov in a six-game match -- the first time a reigning world champion lost a match to a computer opponent in tournament play. Kasparov hasn't just battled IBM, he challenged other supercomputers and in a highly successful, hotly contested Internet-based contest. Here we look back at the ultimate in Kasparov vs. machine battles.