These are done wide open (2.8-3.5 depending on the focal length) with the dogs coming toward me. It is fairly difficult but, I have done it so much that I have learned how to do so with my E-1. I have a harder time with the E-500 as it is just different enough in handling and I don't use it nearly as often. I know another whippet owner who prefers the E-500 for these sort of action shots as she started with that camera and the E-1 came second.
I think it is all about learning how your camera handles. Occasionally I get a misfocused shot, but, that is fairly rare.
I do have to comment on a toy dog owner that has a D2x that is going to sell it and buy a 1DmkIII as he feels Nikon is just too slow focusing to catch his little dogs. I pointed out I get the whippets fine with Oly, which is reputed to be slower. He said his dogs were smaller therefore more difficult.(how can a little toy dog be more difficult than dogs going 40mph toward you?) Honestly, I don't think changing systems is going to help him much. If you can't get action with a D2x, well, I don't think it is the cameras fault
The first two shots were just lucky that I hit them in those stride points. I could use a spray and pray technique, but, coming from an OLD canon TL QL that was fully manual, I can't seem to make myself do so. I would probably get more like that, but, would have to chimp TONS