Check out Dpreview for a very good review of whatever camera you want.
follow this link
http://www.dpreview.com/reviews/sidebyside.asp
to a page on Dpreview where you can select the cameras you are interested in and have a direct side by side comparison.
The D40 is still a good camera choice which provides very nice straight out of the camera very good pictures. so it has the advantage of cutting down on the amount of PP you need to do for yoru pictures. study your lens needs and see if there are such lenses which have built in focusing motors and maybe then you would decide to get the D40 as it's prics and size are hard to beat.
For me I still have my D70s and am happy with its size as I like a bigger and heavier camera. I even added a vertical grip with two batteries to make it heavier as I feel it helps balancing the camera better with heavier lenses.
Study your choices and most importantly go to a camera store and hold whatever camera you think of buying and see if you like how it fits in your hand and if you like the buttons display the menu... the D40 is also bad in that the you have to scroll through the menus to reach some of the frequently needed options.
Bottom line each camera has its pros and cons and its best to know them in advance then to regret your purchase later on.