Bill Reiss has posted the first two parts of his series on building a Silverlight game called SpaceRocks. On step one he describes
the game loop and step two is dedicated to
Sprites.
Most games require a game loop which is simply a method that executes on a timer. This method can contain things like input handling, repositioning sprites, checking for collisions, or spawning particles. In Silverlight there are a few options for this, including using a zero duration Storyboard, a DispatcherTimer, or the CompositionTarget.Rendering event.