I have been thinking about upgrading my Rebel xt. So far it has served it's purpose, I am a slightly advanced beginner (?) I had someone tell me that I should just buy new lens for my current camera, rather than investing in a new body. The reason is I am on a tight budget and was only considering the XSi or the T1i. Their opinion was my Rebel XT can do what these cameras can do, with the right lens. Its this true? I really need advice!! I mainly shoot portraits outdoors of kids and families, with one upcoming small wedding for a friend.