30 day challenge- something green

Well 27 day challenge because I just found out about it so I'm joining in today :)
Today the weather is miserable out so I'm staying in, drinking a lot of tea and getting on with writing the asthma essay that I have been putting off over Christmas.
I might go see the Girl With the Dragon Tattoo tonight, I have the book but haven't read it yet, is it a good idea to wait and read the book first?