I have been in a similar quandary but with the D3100 vs the D7000. While the D3100 would probably serve me fine, I can't pass up the idea of having the D7000 and all it's advantage. Plus, I currently shoot with a D40 (which I am very happy with, I just want a second body) and I kinda want to jump up into something a little higher in the Nikon lineup. the D3100 just seems like a newer version of the D40.
At this point, I am also leaning toward the D7000.