I remember reading that in On Writing also. I think it's the one he wrote in a frenzy with the typewriter balanced on his knees in the laundry room or something, right?
And it really was a great story. Not only could I recall nothing about it, I figured my perception of it would be WAY different now since a 12 year old's brain just doesn't perceive things quite the same as a 38 year old. haha. From the beginning, with the way it told things from Cujo's perspective (before he became rabid), I thought: "Damnit, this book is gonna get me this time around".