Thanks for the replies, and the compliment. The subject is Kurt, one of our three Pugs. It was taken at the dog park under overcast late afternoon skies so available light was starting to become a problem.
Just poking around with the D100 I see it does have that feature where I can adjust the aperture/shutter while in P mode, so now I have something else to fiddle with. One of these days I’ll crack open that tome that came with the camera and really figure out what all those buttons and switches do.