Book Before Movie or Movie Before Book?

My mom gave me a copy of The Girl with the Dragon Tattoo a couple of months ago. I haven't read it yet.

I plan to see the movie, probably on DVD and I've been debating whether to read the book before or after I watch it.

If I read the book first, I’ll already know what happens in the movie, more or less. I think also, reading the book first gives a person feelings about whatever may have been left out of the movie or added in.

However, being knowledgeable about the story also has advantages. I would probably know more about character motivation and such.

I recently read the first Harry Potter book and I found that there were details that weren't included in the movie or I just didn't catch them.

So, I guess what I do will depend on how I want to experience the movie. Do I want to be knowledgeable while sacrificing suspense or should I wait and see what extra tidbits I pick up during a post-movie reading?

- LR