hi! lol. it's me from the D90 thread.

anyway, regarding your question. I supposed the easiest way to make a stop motion animation using something from the CS5 suite would be using Adobe Flash. It's really straight forward and all you have to do is insert the photos in the frames. since you're just doing this using pictures and there's no flash animation and such, it should be fairly easy to learn how to use the basics quickly.

below is a stop motion animation i made last year using Adobe Flash. it was for my college assignment.
http://www.youtube.com/watch?v=5L_T9ZYDB9A

forgive the somewhat crude animation, i was in a hurry. deadline and all.

anyway, hope this helps! i'll be open to any questions if you need any answered. good luck with your animation!