I currently own the Digital Rebel Xt w/ the kit lens and also own a 50mm 1.4 lens. I would like to purchase another lens and after reading all the reviews I am really confused. Unfortunately I don't live anywhere close to a good camera store. What I am hoping to buy is a good walk around lens that will deliver sharp, clear pics. With my current lenses I am frequently disappointed not having a wide enough lens and also need a good lens to take indoor low light shots of people. I am not sure if I will be able to purchase one lens to meet my needs or will I eventually need to purchase two lenses? Maximum cost cannot exceed $800. I want to get good lenses that I will be able to keep for a long time. I was thinking about the Canon 17-40mm f/4 L. Any opinions would be greatly appreciated.