what a mess of answers... =P
I don't get myself in these type of discussions but here I go...
my opinion:
D70, D40, D40x, D60, D80 have all your pro and cons!
all these cameras work with almost any Nikon lenses produced since the 1970's, some in manual mode only, some in manual focus only, it doesn't matter, you'll understand one day.
D40 6mp ISO 200 vs D40x 10mp ISO100 = D40 wins, better camera for all around photography + low light
D60, D80 = not good value for money, I've got the D80 and it's not worth it, the D200 is good camera.
Back to the D70 vs D40 question it's a very difficult decision to make, try to get your hands in both of them and try it before buy.
don't listen to other people advice so much and try to decide it for yourself, research, research, research again.
http://www.flickr.com/groups/51903796@N00/discuss/72157606285132287/
http://www.flickr.com/groups/nikondigitallearningcenter/discuss/72157609863275997/
http://www.flickr.com/groups/d200/discuss/72157594400302787/