I'm not sure if this is directly related to your issue, but I recently upgraded from a Panasonic ZS7 point-and-shoot to a used D200 with a 50mm f/1.8G lens and it has been absolutely outstanding. I suppose if I already had this camera for years I might be wanting a better one, but for me the reason for purchasing the D200 in the first place was because our ZS7 took such grainy indoor photos that we thought we would have to go to a studio to get decent pics of our 10-month-old son. We could have bought a newer camera, but for just taking better pictures the D200 fit the bill very nicely.
So I guess my question to you is, what are you wanting to do with a newer camera that cannot be done with your D200? Unless you're looking for some specific features of the D7000 that will help your photography (or videography, since it does record at 1024p), you might keep the D200 and invest in some lenses like others have suggested.
But then, I'm all new to this DSLR world so I might have no idea what I'm talking about