WOW! I appreciate everyone chiming in so fast I appreciate that, what I am trying to achieve is the speed and low light, I recently went an indoor barrel racing event and couldn't get an good shots due to the poor lighting. Also I like the idea of selling the 70-300 didn't really think that route because I rarely use it anymore and especially if I were to get the new lens. As far as the D7000 I also like the weather sealing and the built in motor for more lens options but as well as the overall build of the D7000 seemed sturdier and more like a pro camera than my D5100, I also heard that it has a better processor and better overall internal parts. Keep the opinions coming I like to see what other peoples logic is. Thanks again.
While I am at it here are a few of the barrel racing shots.
View attachment 16070
I found that tough conditions to shoot like your shot above requires more planing. Don't mean to tell you anything you already know. But with the action coming directly at the camera a fast shutter speed is required to prevent blur but the low light pulls the reins in on that plan. I try to avoid shots like that and look for angles where the action is moving across the frame and pan with the subject.
My way of thinking is part of the goal of the capture is to demonstrate the low light. Why shoot in the dark and fill it with light from a flash so it looks like it was taken outside at mid day?