I've seen a demonstration of the package that's included standard with Macs; very, very nice.
For free and for a Windows PC, Photo Story (now at version 3) is capable of helping you produce snazzy slideshows with accompanying music and so-called 'Ken Burns effects' (automated zooming and panning of subjects in a still), and more. One shortcoming is that you can't easily sync the pictures to the music; that's available in the pro version which isn't free.
If interested,
here's a link.