I am just about to buy a Canon 40D and am now wondering what the best startup lens would be. I only have the money for one lens at this point and need the best walking around lens for the camera. I've read that the 50mm is a must have and am considering the 50mm 1.4 but not sure if its worth the $200 more than the 1.8. Should I save the $200 for a better lens? And any other suggestions for a good startup lens?