#1. "RE: Sample Images D7000 vs D200" In response to Reply # 0 Thu 04-Nov-10 12:14 AM by pdekman
Now having both cameras, I would say ISO800 with the D7000 is still in the 'don't worry about it' category. Perhaps equivalent to ISO250 or maybe ISO320 on the D200. Easily corrected with mild noise reduction.
DR and color hold up really well at the higher ISO's as well. Much better than the D200.
EDIT: For what it's worth, I looked at my latest Lightroom3 ISO defaults between the cameras. Not a direct photo comparison, but here's the Luminance NR values I independently selected for each camera.