Anyone have experience with these lenses?

These are some of the lenses I'm considering. If you have any experience, knowledge, or comments you can share about them, please do so!

A) Sigma 70-300mm F4-5.6 APO DG Macro(Motorized)
- http://www.sigmaphoto.com/...ized-nikon

B) Sigma 70-300mm F4-5.6 APO DG Macro
- http://www.sigmaphoto.com/...acro-sigma

**Between A & B, what's the difference between motorized and not?

C) Nikon 55-300mm f/4.5-5.6G ED VR AF-S DX Nikkor Zoom Lens for Nikon Digital SLR
- http://www.amazon.com/...003ZSHNCC/

** C is probably what I'm leaning toward.

Some points:

1) I'm limited by budget. These lenses are all in my price range. I'm not going to spend more than 500 bucks, period.

2) I'm a hobbyist and bird enthusiast. I know that I'm not going to get perfect photos. I'm just going to do the best I can, I'm not new to wildlife photography (though I lack technical knowledge) and I'm happy with 1/1000 photos turning out good. I've been using the 18-55mm lens that came with my camera, and I've taken some great pictures with it. I enjoy the process, I don't need a perfect result.

3) I use a Nikon d60 digital slr, if that has an impact on which of these lenses might be the best choice.

I've asked about which lenses to get, and got some good advice, but I'm specifically asking about these (or comparable) lenses.

The difference between A & B is simply in the mount (as can be seen from the specs). Nikon uses a focusing motor built into the lens and it is A you need for a Nikon camera. B is designed with Canon/Sony/Pentax mounts which cameras have the focusing motor in the body and is therefore not for you.

It then becomes a choice between A & C. The purists will tell you to use a Nikon brand lens, but there's absolutely nothing wrong with Sigma lenses which are used by 1000s of hobbyists the world over. The choice is yours.

I have used the (B) and I was quite surprised with it's optical quality. The difference between (A) and (B) is that (B) will NOT autofocus on D60 since it doesn't have a built in motor so you'd have to go for the (A) if you decide to go with SIGMA. (C) offers VR and will let you get away with slightly slower shutter speeds as it'll decrease vibrations. Go for (A) or (C) and get whichever one is cheaper. Start playing around with either one and when you reilise that you need a faster lens start saving up for NIKON 70-200MM F/2.8G ED VR II