I have only taken a few snaps when I received my 40D so I will note there is a stupid default mode and avoid it .... my old XD5 has only 4 modes : autoapeture , autoexposure , flash and manual (I always used manual by preference as I think I know more about getting a camera than a camera control chip will ever know).
I can see , when I get my EF 70-200 f2.8 L IS USM and start using the 40D, I'll be on a steep learning curve (this being my digital camera of any kind).
Thanks for making me aware of this issue.
I think it is also worthwhile removing the battery from the camera when not using it, I've always done this with my XD5. Nothing worse than a battery leak inside something expensive - I found that out when it happened to my Astrosystems lasercollimator (luckily I am on friendly terms with Astrosystems and they repaired it very cheaply and made it better that it had ever been before.