I would go with the D7000. I love my D90, but the D7000 has newer technology, plus is a tougher build than the D90. (More weather sealing and metal in the body)

Although, you can get a used D90 in really nice condition for pretty darned cheap these days, if price is a major factor. The D5100 is also a very nice camera, despite Ken Rockwell loving it......lol. (JUST KIDDING, KR fans!!!!)

An excellent place for more, and extremely detailed Nikon info is Thom Hogan's site:

http://www.bythom.com/