I came across an interesting thing called "Thinking Machine". It is a Java based Chess game - where you will see the actual moves considered by the Computer (Expert System - my research topic!) before it actually moves it. Even though, I am a kid in Chess - fascinating!
Good, easy way to understand why Deep Blue was a challenge to Kasparov (By the way, I heard he has quit the game to enter in to Politics. God save Kasparov!)