What are the main differences between Nikon D40, D80, D100?

I am trying to decide between these 3 cameras. D40, D80, D100. I want a digital camera that takes the best looking photos, action photos of sports or animals in motion would be great if thats possible. I would also like it to have a nice zoom. I want to be able to blow up a photo poster size if it turns out nice. Any suggestions would be great since I dont really know what all the specs mean yet.

simply choose the D80..more superior tha D40 and D100.

The D100 is older technology which is surpassed by the other two cameras named.

The D40 has 6mp, and is beginner-friendly. The one shortcoming is the lack of an autofocus motor in the body, limiting lens choices if you want AF.

The D80 is 10mp, has a built-in AF motor, and has multiple settings for the growing photographer. The higher resolution will give you more flexibility in enlargements and cropping. This camera is the best of the 3 you've named.

As far as zoom, that's based on the lens(es) you choose to attach. I'd recommend a Nikon 70-300mm VR for a nice sports or "animals in motion" lens. In low light, the Nikon 80-200mm f/2.8 excels.

The D40 is a 6.2MP entry-level DSLR with basic features, but no auto-focus servo, so it only works with newer AF lenses. The D80 is a 10.2MP intermediate level DSLR with the AF servo and some advanced focusing, metering and exposure features. The D100 is the now obsolete version of Nikon's professional DSLRs that is 3MP and has even more features, but is now considered outdated, it was replaced by the D200, which is being replaced by the D300.

I'd get a D80.

See my answer in Photography. The difference will be in cost and build but want make any difference in image quality.