I would stay with DX and would save for better glass. And i don´t consider the D7000 that "huge" upgrade from the D90 (i was in the same boat as well 2 years ago and decided to keep my D90). I'd rather have a D300s than a D7000, though the D7000 is newer thecnology than the D300s.
Nikonians!!! My best investment made after my camera!!!