Upload & Sell: On
The first time I held a D300 coming from a D7000/D90 I was so amazed by its build quality. I don't think there's a DX camera with a better construction. You also get 8FPS (with the grip), 9 shot bracketing, 51 AF point system, better manual controls, full magnesium body, etc... It's a professional DX body which is almost exactly the same as the D700.
So my advice if you need a tad better low light performance, video and the extra 4 MP then it's the D7000. Otherwise, the D300 is ahead in every other aspect and it's even cheaper. Of course this is subjective and only my opinion