No, Sarah Michelle was good in Cruel Intentions, but Cruel Intentions was a remake of Les Liasons Dangereuses/Dangerous Liasons, and in all the adaptations, the SMG character is just as evil. Glenn Close played that role and Michelle Pfeiffer was the Reese Witherspoon character in Dangerous Liasons. I even think Annette Bening did it at some point.
You wanna see a movie, with a real, evil white woman that was just off the wall, she was so evil, awful, spoiled, entitled, evil, awful? You should watch the film adaptation of "In this Our Life" with Bette Davis and Olivia De Havilland. Nothing was sacred to the Bette Davis character, not even her sister's husband. She just did whatever she wanted, no matter who was in her way. Sometimes we tend to think that the whole "evil bitch on film" thing is a more modern phenomenon, since I don't know the 80's with Dynasty and Dallas, but no, there were Alexis Carringtons in the film noir era.