These last four are technically far better - they're all very crisp, pin-sharp. The shutter speed is fast enough to capture the motion (for example the flying snow). Focus is spot on. The light is pleasantly chosen. There's nothing really to complain about technically here - congratulations! Compare with where you were two months ago and it's quite amazing the difference.
You are benefiting from relatively favorable conditions - these are all taken in relatively bright light, making it feasible to use 1/250th shutter speeds without having to resort to higher ISO or a faster lens. But having taken advantage of the light, it's all there.
> If you had taken the same shots with your basic camera and again with your top of the range camera would you expect the same degree of variation in quality between the three images in each case?
I think they both would have turned out almost exactly the same result. I could zoom in a bit more on the details on one than the other, but until I made a relatively big print from either of them I doubt anyone would notice the differences. Big in this context means at least 11x14 and probably a bit bigger as these are right on the money for sharpness. I wouldn't expect a big difference between them until the conditions got somewhat adverse. For example if these had been taken at twilight, there'd be a big difference between the D100 and D3 in terms of AF accuracy in low light. Or if the kids were running around dodging snow balls, again the more advanced camera would be significantly more likely to keep the intended target in focus, even if I didn't keep the action framed consistently. (If I keep the framing constant, they'll both get about the same shot.)
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!