NOT THE PURPLE DINOSAUR: I'm proud to report that, at 2 1/2, my son C.J. knows only one Barney, and his last name happens to be Fife. I've been Tivoing old ANDY GRIFFITH episodes, and the boy just loves 'em, especially when young, face-contorting Opie labors his way through his lines. Now I just have to get him to appreciate the profound physical comedy of Dick Van Dyke and John Ritter.