Actually, I find graphics gale quite reliable even in it's free state. However, I would simply suggest getting the GIMP 2.6 for animation. While it's undocked windows may be unfamiliar to some, I've gotten used to it. All you do in gimp, is load your stills into different layers, then save it as a gimp animation. Simple. Gimp also does have some dirty tools though. So it might not be that good for pixel art.