When you finish Goblet of Fire, if you want more background info you could try Beacham's Sourcebooks for Teaching Young Adult Fiction: Exploring Harry Potter by Elizabeth D Schafer. It's not actually approved by J.K. Rowling, but extrememly interesting nonetheless. There's a lot of information about everything you could possibly imagine concerning the series. One of my friends took a Children's Literature class this semester and focused her project on Harry Potter and this was the book her teacher recommended. I enjoyed it. I can't wait for the movie also. I've read the books over and over and I'm beginning to go through withdrawal. I want the new book already!!!