Books first, movie second
If you have that option. If you have seen the film and not read the books because you don't think it's worth it, go out and read them because it is
Though I do have to admit that reading the books first did take some of the suspense out of the films, and of course when you read the books you have your own images of what certain scenes look like, and when the movie images don't meet your personal images you can become somewhat dissapointed. But when you read the books first you get Tolkien's true and complete story, which is the best version, by far, in my opinion. The film is great, but the books are wonderful.