YORKTOWN HEIGHTS, N.Y. - It's the size of 10 refrigerators, and it swallows encyclopedias whole, but an IBM computer was lacking one thing it needed to battle the greatest champions from the "Jeopardy!" quiz show. It couldn't hit a buzzer. But that's been fixed, and on Thursday the hardware and software system named Watson was to play a practice round against Ken Jennings, who won a record 74 consecutive "Jeopardy!" games in 2004-05, and Brad Rutter, who won a record of nearly $3.3 million in prize money. "'Jeopardy!' felt that in order for the game to be as fair as possible, just as a human has to physically hit a buzzer, the system also would have to do that," IBM spokeswoman Jennifer McTighe said.