Im looking for a telephoto lens for my D60.
Ive spent a bit of time searching around for what is available and trying to get an understanding of what all the numbers and letters mean.
Even had a good read through the Nikon section here on the site (I really like the Similar Threads function!)
I am really just learning in full manual and shooting lots, experimenting with various combinations of settings through ISO, shutter speed and aperture.
(Learning just as much from what doesnt work as what does)

What I currently have:
Nikon D60 with the kit lenses: 18-55 AF VR and 55-200 AF VR

What I want:
A telephoto out to at least 300 or maybe 400
I think I also want the auto focus as well (but have noted that not every lens will run autofocus on the D60

What I want to shoot:
Motorcycles (moving ones! on the track and out on the roads)
Martial arts and combat sports (medieval reenactment - think swordfighting)
Wildlife
I also enjoy macro stuff, but really very amature about this!

What can I spend:
I certainly dont want to go over $1000 and would prefer to keep it under $500

I do have a tripod but dont always carry it
I do have muscle shakes in my arms / hands

I honestly think the Nikon lenses will be out of my price range but is it worth buying the cheaper lenses such as Tamron and Sigma? (considering the results)

I have looked at:
70-300mm 1:4-5.6 DG MACRO "With Built-in Motor"
70-300mm AF Di LD Macro (A17NII)

any other things I should know?
Other possibilities?
Any suggestions?

Very much appreciated...