hi! i currently have a canon xti with the kit 18-55mm lens and i have since purchased the 70-300mm f4.5-5.6 and 50mm f1.4 lenses. most of the work i am doing is shooting in low light settings at live music concerts but i also do a lot of street photography and travel photos - landscapes, sunsets, etc. i'm thinking about either upgrading the body, or purchasing a new lens. the lenses i have been looking at are the 17-40mm f4L and the 17-85mm f4-5.6 to upgrade the kit lens. i have heard it is better to purchase lenses/upgrade the body but i think i am ready for something a little better and would like to upgrade from the rebel asap, however if it's a better use of money to buy a better wide angle/mid range lens i will hold off on the body upgrade (for $$ reasons of course) any thoughts would be greatly appreciated!!