I'll add my modest experience with slide-show software.

A few years ago, I started with PhotoStory3. I still like it.

Last year I learned Windows Movie Maker basics on my XP machine,
at first primarily because I was converting old AVI files to WMV..
It is also stable, and mixes video and stills OK.

More recently I discovered that WMM on my Vista Premium machine
has a very different interface, and is called Movie Maker LIVE.

Two months ago I played with Animoto for a while.
Fun, not quite enough flexibility, maybe too much Pizazz.
Very slick for cranking out little 30-sec bites for free.
Don't use their AP via Facebook, go straight to Animoto.com.

Last month I finally discovered the feature in PICASA 3
to make "movies". I love the "Face Mode" Pan and Zoom transition.
Very nicely integrated with my collection which is already in PICASA.

Today I made a few videos to upload to Facebook,.
and chose to use XP-based WMM. I like the many choices
it gives in the trade-off between bit-rate and file-size.

I thought all this experimenting would lead to a preferred
software., Surprisingly I think I can see using each of them
in diffeent situations for the near future.