Have a look at PhototoMovie (http://www.lqgraphics.com/software/phototomovie.php). It is the closest I've seen to ProShow in terms of its features. More than just a lilbrary of transitions, PTM permits you to control the timing of the transitions in relation to the soundtrack, include voice overs, and the kicker feature is the ability to draw paths through the image, ie. Ken Burns. For historic photos with lots of interesting details, you can zoom in on a specific element, and move through the image. Really slick and only $50!