I have a D80 and a D40X, and I am probably going to sell the D80, the D40 is smaller, lighter and just as quick in operation, the image quality is identical, actually the JPEGS straight from the camera are actually nicer from the D40X, more consumer friendly and require less or no post processing, and the big big advantage of the D40X over the D80 is the metering.
In my opinion the matrix metering on the D80 is rubbish, the camera is excellent in every other respect, but the quirky metering leads to way too many overexposed shots, I dont/cant use matrix metering on the D80, most require between -0.3 to -0.7 EV compensation even in evenly lit situations....Oh Joy oh Joy, this seems to be completely resolved on the D40X with great reliable metering, I have experienced no issues, the D40X metering is consistent hooray !!
If you are happy with the D40(X) viewfinder (which is good but even better on the D80)...are not worried about no AF motor for older lenses (dont even worry about it if you dont know what this means), then save yourself at least £200 and get the D40X...or even consider the even cheaper D40 (theres not much between the two for image quality)
Oh and the kit 18-55 lens is really pretty good with little distortion at wide angle.... Most people need not go to the expense of the D80 (which is an excellent camera please dont misunderstand me) in my opinion, highly recommended