If you wanted to make an animated movie then there is some free open source software that is very powerful that you could used called Blender. http://www.blender.org .I know of three really cool short animations that were made with blender that rival anything Disney makes in my opinion. Especially the last two below.
The first one that was a pretty big hit online was Elephants Dream http://www.elephantsdream.org/
The second one that I know of was Big Buck Bunny. http://www.bigbuckbunny.org/ . I really like this short story a lot and it's funny.
The last one that I have seen is Sintel. http://sintel.org/
All three were created by a small team over a long period of time, typically about a year. As you can see this software is very powerful and is capable of some really cool animations. Blender's learning curve is quite high though. It is quite possible to make a full length animated movie for free using Blender, but it would require quite a few people to get it done in this lifetime.