The Nikon D40x delivers very clean images at 100 and 200 ISO with only the slightest texture from noise and noise reduction visible at 400 ISO. This texturing becomes much more obvious at 800 ISO and above.
Despite its higher resolution sensor, the results below are very close to the D40 samples, although the lower resolution model arguably has a slight edge at 800 ISO. It should be worth noting though the artefacts on the three 10 Megapixel models will appear slightly smaller than those from the D40 when images from each are printed at the same size.
It's also interesting to compare the D40x against the D80 here. Both cameras share the same 10.2 Megapixel sensor, although employ different image processors - and different default processing strategies. It's clear from the crops below that the D40x image processing is designed to match the D40 to deliver punchy, vibrant images straight from the camera. The D80 and Canon 400D / XTi default settings deliver far more subdued images. It's all a case of personal preference though and all the cameras allow adjustments.
As always though, the flat colours of the Gretag chart here can hide a multitude of processing sins, so to see how the D40x handles real-life subjects at each of its ISO settings, head to the next page.