Read the book, don't wait for the movie

I've somehow watched three British literary adaptations in the last week or so; could explain why I haven't been posting here or even catching up on my various Challenge books! I feel as if I've been on vacation: I've watched the newest Bleak House, Enchanted April, and the latest Jane Eyre (with Toby Stephens, yum). All three are quite wonderful. I've always loved Enchanted April for the way it follows the book so closely, and captures the loveliness of the original story. The casting, costuming, locations, and production values all mesh to result in one of my favourite films, which I view frequently. However, both Bleak House and Jane Eyre take some liberties with the text; perhaps because the source novels are so very large. Although it usually bothers me when this happens, in this case it seemed to work very well. The filmmakers were following the spirit, if not the letter, of the novels. Nobody can do adaptations like the Brits. Perhaps these excellent productions should be called "Brit-erary Adaptations"!
My literary/film travels were abruptly halted when I tried to watch a North American production of The Return of the Native (a Thomas Hardy novel that I loved), but which didn't really succeed. It was really too bad; some marvellous actors - favourites like Clive Owen, Steven Mackintosh and Joan Plowright - but a sadly unhinged result. Once again, let the BBC do these kinds of things!
I haven't read Bleak House yet, but I'm very familiar with the others as novels. When a book is made into a movie, do you prefer to watch the film or read the book first? I've read books as a result of watching good films -- for example, Our Mutual Friend (in which Steven Mackintosh appears again, in a wonderful role) or North & South. Anyone else have a favourite adaptation or two?

Update: Check out some other opinions on the subject of adaptations - by Superfast Reader or by Jill.