Here are tests that show the resolution capabilities of the Nikon 80-400mm f4.5-5.6 AF VR. These samples are center 100% crops from the 10MP Nikon D200 (which has an APS-C sized sensor), and is equivalent to looking at prints greater than 3 feet wide.

The 80-400 performs very well in the 80-200mm range, with 135-200mm at f8 or f9 being the sharpest range of this lens. 300-400mm is a little softer but is still decent. The 80-400mm is diffraction limited on the D200 at about f10, as can clearly be seen in the tests. The bottom row has 100% center crops from the Nikon 50mm f1.8 AF-D taken at f4. The Nikon 50mm f1.8 AF-D at f4 out resolves the 10 MP D200 sensor and the samples are only for comparison purposes.