Aquarium Screen saver improvements

The aquarium screen saver that ships with XP Media Center is good, but the
fish don't seem quite realistic enough. I realized it's because they don't
exhibit any feeding behaviors. The screen saver should feed them
periodically, it is relaxing and pleasant to see fish eat. Also, they might
poop, but that should be optional because some people don't like to see poop,
even though it would be subtle and add realism.