One thing Buffy the Vampire Slayer's Sarah Michelle Gellar knows how to do is scream. And she's been doing a lot of it this summer while making two movies, "I Know What You Did last Summer," a thriller about four teens with a dark secret, and "Scream 2," the spook-spoof sequel starring Neve Campell and Courteney Cox. Both were written by Kevin Williamson (whose new WB show, Dawson's Creek, is already triggering buzz). after a chance meeting on a plane, he decided he had to cast Gellar in "Scream 2," (she was already in "Summer.") "Yes, yes, it's true," says Williamson. "It's a juicy little part and she's rocking. But I didn't have to push her hard. [Director] Wes Craven fell in love with her, too. I now want her in every one of my movies." TV Guide, July 26 - August 1, Hollywood Grapevine by Mark Schwed, pg. 10