Hello, smithun81! Welcome to the forums, enjoy your stay!
The D300s is still a current model
That's debatable, one could argue that the D3x is still a current model because no "true" successor has been released, but who would buy one when the higher resolution lower priced D800 is available at a much lower price point with much newer technology?
All that the D300s has going for it is the build quality and frame rate. It's built like a pro body, which it should be, as Nikon was going after the prosumer market when it was released. However, the D7000 beats it out in just about every other area, its IQ blows it out of the water. However, if you can still find a D300s at a good price and you personally like the design and the way that it fits in your hand, then go for it.
Either way you won't be dissapointed, and both would be a massive upgrade over your D40x. But honestly, the D7000 is much more future proof and although it lacks a bit in the frame rate department and is smaller, its IQ definitely doesn't dissapoint. If you want to spend a few more bucks and don't mind losing one frame per second, the D600's a good choice, it's essentially a D7000 with a full frame sensor.