Stop-Motion movie

I want to make a simple Stop Motion movie on my mac. It will be very simple, as a dialog between 2 "playmobils" sitting in a car.

So, the animation will just only be "mouth movements" and "eye winks", to make them look "alive".

What would be your advice about the software to be used to paste different eyes and mouths quickly and easily to create the successive snapshots ? (Consider that I have no budget to do this, so avoid the answer "Adobe CS 4" ;-). To make the editing, I will use the (outstanding) iMovie. (what else? ;-)

• Which App would you use to create the different mouth shapes ?
• Which App would you use to paste them on the unique picture of the 2 playmobils ?

PS / I know it's not really a Q&A question, but instead more a "advice request", but please do not close it to fast :-)

Solution 1:

Regardless of what software you use to edit your frames (Be it GIMP, Acorn, Pixelmator, Photoshop, etc.), the best software I’ve seen to actually work with the movie and make it “live” is Boinx’s iStopMotion.

Not free, not the cheapest, but very good quality.