It's an overcast day today. Here's a series taken with only the light from a north facing window in the room.
All photos were taken with the AFS 18-200mm set to 200mm at f5.6. The D700 was on a tripod. All photos were shot in raw at ISO 800, 1600, 3200, 6400 and 12,800. No post processing except for reducing the size in CS3. The first 5 photos are the full DX frame. The last two photos are crops and not down sampled.