HI Warren,
In general, I don't disagree with anything Amberglass or Kent have said.
However, to get the most of what you currently have, and knowing the D5000, I would say for a re-shoot, use fixed ISO at 3200 (it's fine*) and shutter priority and set it at 1/250.
There will be times when the action goes into darker spots when you'll probably run out of aperture and get under-exposed shots, you just have to bring these up in PP and noise reduce (as *).
These settings should give you a far better chance of some shots you'll be happier with.
If you do look for 'faster glass' and are tempted by the older lenses that require manual focusing, I have to say I'd personally think twice for this subject matter, because I think trying to manually focus on moving athletes through the viewfinder in poor light. It will be very tricky and I believe will result in out of focus shots - because with aperture wide open there's going to be little depth of field to get away with focus errors. However, Amberglass has done it for real and I haven't, so maybe I'm overlooking something.
Cheers,