I would buy an used 70-200 2.8 VR1. I don't have a D7000, but do have a D90. Though the D7000 is a good upgrade from the D80, and D90 as well, the best investment you can make is on the best lenses available. I find that when i offered an used D70s to my girlfriend and was quite surprised with the excelent IQ from files, almost as good as the ones i can achieve with my D90. BTW, if you take just a minute to fill your profile, concerning your equipment, it will help to get excelent advice provided here in Nikonians (not from myself, ).
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