Those are really nice shots. I really like the one where he is to the left of the image.
I own a Nikon D80; which I am selling on E-bay because I bought a professional one in Canon. It has many of the same features as yours. Your right about the choice of continuous shooting. That can be helpful when trying to capture a moving object. Something you might want to try is panning while shooting. Follow your subject with the camera as you shoot. You may have to practice this for a while to match the speed up correctly but with an 8GB card, you can do a lot of practicing. My guess is, if you really love photography, you will get good at it if you keep shooting.
And, T is correct about the lens choice. You want one that is fast and the 50mm is a good choice. That is not a zoom lens so if you want to have a closer shot or one further away, you have to move closer or further away. They are called prime lenses and even though they don't zoom, they are better lenses than the zooms.
I hope this was helpful to you.