I've read all of the Potter books that have been released. I didn't start reading them until well after the 3rd Potter movie was released. I felt the first book and movie were nearly identical, but more thoroughly enjoyed the ending in the book than in the movie. The Potter books get progressively better and better. Like Kenny, I rarely ever read a book after I've seen the movie, mainly because the books bored me. However, the level of detail in the Potter series and the differences between the books and the movies are significant enough that they maintained my interest. I'm now waiting for the 7th book to be released.
The 4th Potter movie was a bit of a disappointment to me, it left out SOOOOooo much of the book, that the movie could have passed for any old action flick that was released last year. In order for the 4th movie to do the book right there will have to be an extended version of the movie on DVD that would add another 2 to 3 hours to the theatrical release. Unfortunately, I don't think that'll happen.
The Narnia books were all rather thin, at least the editions of the books I've read were. So, the movie has an easier go at keeping the story of the books without loosing what was written. In my opinion, it's the lack of complexity in the Narnia books that is in their favor when being converted into a movie. That said, there were a couple of spots in the movie that were altered from the books, in order to make the scenes more dramatic... One thing I remember reading but don't recall seeing in the movie was Aslan reviving a giant. However, the giant was barely in the book. So, there's no real loss there, IMO. The other thing I can remember from the book but not in the movie was Reepeecheep (erm, forgot how to spell his name), the king of the talking mice in Narnia. I don't remember seeing a single talking mouse in the movie.
My company published the games for Narnia, and we had to deal with the CS Lewis estate when it came to keeping, changing, or adding things to the story. They're smart people and I thank them for not allowing certian things change in the games for the sake of a lower ESRB rating.
My point is the CS Lewis estate had the final say so on what was or was not in the movie (and games), and I think they did a darn good job of making sure it kept true to the book. Great movie plan on buying it and sticking it next to my Lord of the Rings DVDs /ubbthreads/images/graemlins/smirk.gif