Yes, Disney never comes up with original stories. 
But let's face it...everything popular in America 
is merely a re-make of stuff that was popular in 
other countries. We're not very inventive, when 
it comes right down to it. If you don't agree 
with that comment, you do have to agree that 
everythign that does well in, say Europe, or 
Japan, is immediatly brought over and re-made. So 
I've gotten used to it.

And I wouldn't mind it with Disney...if they 
would just ADMIT it, already! I love Disney as 
much as the next animation fan, but my respect 
for them is not very high, in that respect. If 
they just admitted that hey, it's based off of 
Nadia (obviously...you don't just "come up" with 
a mysterious blue power source off the top of 
your head...).

Two more interesting links (courtest of Kim the 
Terrible):

http://www.animenewsnetwork.com/archives/feature/a
tlantis.php

http://www.animenewsnetwork.com/archives/feature/n
adia.php

-Misha-chan