Where did you find the >1000 D300?
I ask because that's way too good of a price. There's a running scam where they'll sell you the camera with NOTHING for cheap, and then make you pay a huge amount for the battery, charger, etc.
My advice is to go with the D90. Compared to the D300, it's only weakness is being slightly less solidly made, but the image quality is just as good, if not better (same sensor, newer firmware), and it's cheaper and lighter.
Edit - only saw the date on the last post. Disregard if this is way out of date.