All nikon slrs have the same basic control. You can shoot in aperture (my fav) program, shutter or manual. My d2x, d70, and d80 have the same controls. You can take any of them to any level. The difference is features, megapixals (this only makes a difference if you plan on enlarging the photos. If you only want 4x6, 5x7 6.1 megapixals is plenty) and build quality. My d2x is practically unbreakable. Remember like cars these new cameras are all about electronics and there is alot to be said for build quality. No matter which camera you get make sure it's a USA not grey market and take ou the extended warranty. I have no experience with Canon but I'm sure they make great cameras.
The d40 is not dumbdown!