One of our tactics was to allow our kids to see a movie that might be scary only AFTER they had read the book. This, of course, only works when there is a book smile But there is something about the kid being able to put down a book at a scary part, then come back to it when they are ready that helps. And if they then want to see the movie, they know the scary parts of the plot line. I could definitely see using this approach with the Harry Potter movies (and heck, the books are better anyway, at least the first few are for sure... although the movies have gained some quality as they have gone along).