They have to use the World Cup in GoF! Not only does it introduce the Dark Mark but portkeys as well, very essential to the last part of the movie.
J.K. Rowling has her own site at
www.jkrowling.com She's posted what she thought of the movie and other various tidbits.
As far as PoA goes, I was disappointed that the names on the map weren't explained. Although I really like the new castle, I didn't like that they changed the location of the Gryffindor entrance and the Fat Lady, although Dawn French did a good job. The special effects in this movie were so much better than the ones in the previous movies.