So.. that leaves us without a solid answer to the original question: how many Disney movies are actually original stories?
After looking at the node Disney Animated Features I found that the list of Disney animated movies should actually be brought up to 45 (possibly more), not 41. There were some movies that hadn't been created by Disney's Animated Feature Department, but are still considered to be feature-length films or "featurettes."
UPDATE: Okay. Make that 46 animated features. Lilo & Stitch changed things a little. And I'm sure that as time goes on, the number will rise. It's just a question of when, really. But I'll try to update this node with each new original Disney movie as it comes out. If I fail to do so, MSG me and I'll make changes accordingly. Thanks to TenMinJoe for this one.
Of those films, here is a list of Disney originals (in no particular order):
Movies such as Toy Story, Monsters, Inc. and other joint projects with Pixar weren't completely under the aegis of Disney Studios, though Disney not only helped produce those projects, they helped develop them as well.
So. The answer? 26* (or more).
* - If you find that I missed anything, please MSG me with the title(s) so that I can correct my error.
Recently edited on (01/04/06)- thanks to jclast