I am ready to move up from my T3, which I realize is the bottom the Canon line. Within my budget I can manage a T21 or a 40D. I like the 18mp of the T2i, but really want a faster burst speed since I shoot a lot of birds in flight, or try to. I would be willing to trade off the burst speed for more mp, but am concerned with the auto focus. Which is my primary problem with the T3. The auto focus on it is just way to slow. So, what think you all. Is there a major difference, or any difference in the auto focus between the 40D and T2i. When it comes down to it, this will be my deciding factor.