I've come into some money, so I've decided to spend (some of) it upgrading my photo stuff. What I have now is in my sig. I've decided I have some options on how do upgrade. 1) Upgrade to a 40D. 2) Keep the Xti, but get the battery holder attachment. 2) Upgrade my 18-55 kit lens to a Canon 24-105 f/4L lens. 3) Upgrade my 70-200 lens to the 2.8L IS model. This actually isn't an option because I'm doing this no matter what. Is it worth it to upgrade to the 40D? I can probably do that or the 24-105. Both would be a bit of a stretch.