Looking to buy a new camera

I have a 2 plus something year old Sony Alpha 500 with a Tamron 18-250 lens.  As I learn more about cameras and photography I am becomming more aware of the camera's limitations.  So now I am in the market for a new camera.

This is what I am looking to buy.  Can anyone comment on my plans?

1. Nikon D7000 chassis - see

http://www.nikon.com.au/en_AU/product_details.page?DCRPath=templatedata/en_AU/saleable_product_information/data/Digital%20SLR%20Cameras/D7000.xml&CategoryID=gp11zkm9&currentTab=&currentLink=

2. AF-S DX NIKKOR 18-105mm f/3.5-5.6G ED VR glass

http://www.nikon.com.au/en_AU/product_details.page?DCRPath=templatedata/en_AU/saleable_product_information/data/Nikkor%20Lenses/DX%20Format/Zoom/AF-S%20DX%20NIKKOR%2018-105mm%20f3.5-5.6G%20ED%20VR.xml&CategoryID=gp11zkmv&currentTab=gp11zkn0&currentLink=gp11zkn4

3. 150-500mm F5-6.3 APO DG OS HSM glass

http://www.sigmaphoto.com/shop/150-500mm-f5-63-apo-dg-os-hsm-sigma

What do you think of the selection?  I want the 150-500mm lens mainly for my aviation photography.

Cheers and thanks in advance for any comments.