Nikon D3000 Flash For Night Time Outdoor Sports?

I have a nikon d3000 and I'm taking pictures during a night time outdoor motocross event… What would be some good extras to make sure I can get them fast enough and not blurry… I can buy a flash if needed thought i'd get some ideas…

A colleague of mine uses a Nikon SB800 mounted on a long pole which is held by an assistant and aimed toward the area of interest He uses either Radio Poppers or Pocket Wizards to trigger the flash.

You will have to experiment to see which aperture to use so you have a decedent exposure of the rest of the venue so you don't have a motorcycle, perfectly exposed but with a nearly totally black background