This Memorial Day weekend I went and saw the DaVinci Code and X3. Both were great movies and are completely worth the money to see in the theater.
I haven't read the Da Vinci Code yet, but after seeing the movie it gives me a lot of motivation to read it. I wish I could sit here and argue with you which is better, but I can tell you that the movie is highly entertaining. I was happy to see Jean Reno casted into this movie as well, his presence seemed to fit and flow smoothly with the films essence. If the book does happen to be, and it mostly likely is better than the movie, I would still have to recommend it as a great thrilling / mystery movie to go see.
X3 didn't offer as much character development and plot thickness as the other 2 movies, but was still extremely entertaining. I thought Ian McKellen who plays Magneto and is also in the Da Vinci Code was great in X3. His performance in the Da Vinci Code was also flawless in my opinion. It makes me sad to think that this may be the last of the X-Men movies, but it looks like a movie for both Magneto and Wolverine are in the works. The Da Vinci Code might also be followed up by a prequel, which has some potential of being good. All together I was impressed by both movies and would recommend either of them to go see.
Side Note: Make sure you stay all the way through the credits in X3 for a important bonus feature.