I thought the D7000 was relatively new, as in less than 2 years. We have one, and yes, it's very good. And if you've already got lenses for a Nikon or a Canon or whatever, you'll want to stay within that brand. (I'm not a big fan of conversion rings.) The D90 has been around a long time and has gone through many different updates, and apparently is also a solid choice.
If you go Nikon (and this may be true with the other vendors, too), DON'T get a "kit", that is, a Nikon package made up of the body AND a lens. It seems convenient and attractive, but the Nikon "kit" lenses are consumer grade and have a PLASTIC! mounting ring, and it doesn't take much for the lugs on the ring to shear off! (Happened to us!) Buy the body and a GOOD Nikkor lens separately.
That is what I understand, get the camera body that will work for you and spend the money on the lenses.