Thank you, everyone, for all your advice and information! I'm waiting to hear back from Adorama as to what they would offer me for my D90, in exchange for purchasing the D7000 from them. I'm leaning towards just getting the D7000. The backfocus issues made me nervous though.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ “When words become unclear, I shall focus with photographs. When images become inadequate, I shall be content with silence.” ― Ansel Adams