Keep using them on the D7000! If they are autofocus lenses they'll work with no issue... if they are manual focus you can use them just fine too, since the D7000 has an aperture coupling for AI lenses and a non-CPU lens data input. I have an ancient AI-modified 50-300mm f/4.5 lens and while it isn't the best lens optically, it certainly has its look and I do bring it out to use sometimes.
With the midrange zooms at least, you will probably be better off replacing them with a "cheap" crop sensor zoom, since I imagine a midrange zoom and crop sensor lenses in that category aren't too expensive. Though if you are comfortable with the field of view the 28-80 and 35-105 will look on a crop sensor, then hey why worry about replacing them?
The one thing I would definitely recommend to add to your lenses if possible would be the DX 35mm f/1.8... it'll give you about the same field of view as the 50mm lenses on your film cameras, and it's great quality at a very low price.