''Some pig'' Wilbur is still grazing at the Zuckerman farm, but now it's a 21st-century pen, stocked with Charlotte's sassy arachnid offspring and cliquish, petty beasts. His courage and loyalty are put to the test when he befriends the barnyard outcast, a (surprise) black sheep who is then sold away. A sloppy second of a sequel, Web 2 unravels all the charm of E.B. White's classic (not only has Wilbur become a swine who belches, but he sings about it, too). Oh, that'll do, pig, that'll do.