It's all about algorythms. "Taking on a human chess player took one of the most powerful computers in the world at the time. This brute force computing approach allowed Deep Blue to look around six to eight moves ahead. In a closely-fought contest, the machine eventually defeated Kasparov by 3 1/2 games to 2 1/2. Six years later, Kasparov was involved in another contest of man versus machine. This time he played against Deep Blue’s successor, Deep Junior. The result was a drawn series at three games all. The biggest difference was that Deep Junior ran on a machine with about one per cent of the computing power of Deep Blue. Chess-playing algorithms had improved to the point of achieving virtually the same result with a hundred times less computing power."
