Please use the forum search. Believe it or not we've already covered using the D5000 for shooting horse racing.
http://nikonrumors.com/forum/topic.php?id=1392

The AF on that lens also tends to hunt a bit at the long end if the light's not bright enough, which I'd think could be frustrating if you're trying to focus on one or more moving horses either on an overcast day, or if you're shooting at night. As Drab mentioned, the 300 end might still be a bit short, depending on how you shoot.

Best bet? Find a place near you that rents lenses. Rent one, take it to the track for the day, and put it through its paces. Then you'll have a much better idea whether it's the right tool for the job.

Depends greatly on how close you will be to the track and if you will be shooting during the day or at night.

The 70-300 is quite slow at 300mm and will result in shutter speeds too slow to capture crisp action-freezing shots of racing horses at night.

I'm also a bit concerned that if you do not get special access to the track you will possibly find 300mm too short if stuck in the stands.

Excellent Choice!

Hi everyone.

Im new to the forum.

I have decided that my next camera is going to be the Nikon D5000.

Looks to be a very good camera from the research i have made.

I basically want to be able to take good shots of horse racing, horses, etc... as i am a horse racing enthusiast and i would like to see how good i can get at horse racing photography.

I have been looking at an additional lens. Would the Nikon AF-S VR Zoom-Nikkor 70-300mm lens be a good addition when i have bought the camera? ? ?

Many thanks.