I'm planning on getting a 40D soon and am trying to figure out which lenses to get. My glass budget is around 2k. I've been hearing only good about the 70-200/f2.8 IS, is it worth the extra price over a non IS or 4.0? Then I'm torn for a lens with shorter focal length. Should I get a 17-55 IS or 24-70? The price is pretty similar, so what are the advantages of both? Also, how much better are the IS lenses? And is it a bad idea to get 2 lenses with totally different focal ranges? What do you recommend?