Hi Ozzie. The Nikon D80 is great, if not get the D40X. Dont get the D40, get the X version.
I use a Canon 400D. Took it to an airshow recently with a 75-300 Canon lens and got some ace pictures, I can definately recommend that.
Don't forget to shoot with a low ISO speed to try and stop the props from freezing. Many of mine at the weekend were taken with an ISO of 1/1600!!! All the props were just straight, looked terrible to be honest.
