thank you for your advice.... since i am not yet that experienced and not that comfortable with manual controls, will the d80 perform as well, if not better, then the d40 or d40x in "auto" modes? and in practice, walking around with a body of its size/weight w/ a somewhat heavy lens attached, does it get very tiring? i've been happy w/ the size/weight of my d40 with kit lens...
Hi again, the D80 I believe is equipped with a better light metering system, so yes the camera will perform better in auto modes and other preset programs. The camera even has 9 AF points to autofocus faster (rather than 3 on a D40). The body and weight is designed to be as light and comfortable as possible while still being durable, the D40 is not the best camera to attach a 18-200mm lens because the center of gravity will be on the lens, therefore is will sag down as you wear it around your neck.
The D80 balances out really well, the D80 is slightly more heavier and bigger but not by a massive amount. Also the D80 is nice to have, since it with progress with you, in other words, it can be a decent beginner level but then instantly satisfy the needs of a Pro.
Hope this helps!
P.S. The camera won't tire you out if you carry it all day.