Choice of 4 dslr cameras which one?

Ok so i have narrowed my search down to four cameras.

Nikon D3100 - with 18-55mm and a 70-300mm lens.

Nikon D5000 - with 18-55mm and 55-200mm lens.

Pentax K-x - with just the 18-55mm.

Pentax K-r - with 18-55mm and 50-200mm.

I will be using the camera for mostly wildlife, primarily birds.

Nikon D-5000. If you asked this question one month ago, you just may have got it for Christmas. Superb camera. It's a shame you can't get it with a 70-300mm lens, as you will be using it predominantly for bird photographs.

I'd dump the Pentax and go with either Nikon. Just wondering why you're not considering Canon though?

I just bought the Pentax Kx and love it. But you need to handle each camera for ease of viewing through the lens. I like a field of view that is uncluttered and a movable focusing frame. These are the main reasons I purchased this camera. I also like the idea that the stabilization feature is built into the camera body and not the lenses. Means I don't have to pay for this feature with each lens I purchase.
The camera will accept lenses from Pentax film cameras-another plus if you happen upon a good deal in that area.

I also purchased a Tamron 18mm-200mm zoom lens from Amazon. Tamron is running a $100 rebate if purchased by Dec.30, 2010!

For wildlife, 200mm isn't enough. If you're looking at the Nikon 70-300mm f4.5-5.6 IF-ED VR then that is a good lens. If it's the Tamron VC, that's also a good choice. If it isn't either of these then the lens will only be any good between 70 and 200mm. Useless at 300mm.

The Pentax K-r is by far the best camera of the four, but the lenses aren't quite up to what is available for the Nikon. You may have to look into some used K-mount primes if you want something high quality.

You have done your research. Now investigate The Various Digital camera website.i.e What Digital Camera. Revoo.Compare etc there are loads of them out there and check out the customer reviews Goog Luck