THE Burning Question: Book Before Movie?

Here's what I was thinking as I left CVS. I used to think it best to read any book before seeing the movie version, but now I'm not so sure. In theory, seeing the movie first limits your enjoyment of the book by planting someone else images in your head, thus robbing you of the pure pleasure of imagining the book universe for yourself. On the flip side, no movie can ever compete with your imagination and no movie can capture the intellectual subtleties of the verbal language (for example pictures cannot depict the hypothetical. They cannot express IF, OR, BUT), so reading the book first sort of spoils the movie. I'm very liberal about film adaptations; so long as the movie works, I won't quibble about the actor having the wrong eye color or scream, "How could they leave out everything in chapter 72?" However, I've read books with the intention of seeing an upcoming film version, and wound up taking a pass on the film because I figured they'd just screw it up.(Gwenyth Paltrow cannot be my Emma. Please!)