Dont bother finding it online, its a pretty common game to find in game stores. 64 only has mario as a character, but it does have a different (and better) painting for Jolly Roger Bay. DS has Yoshi, Luigi, and Wario as playable characters, new levels, more stars, better challenges. If you are planning to get the DS anyway, go with Mario DS, if you just want to play the game without buying a DS, rent the original which is fairly commen.
We''re on the moon? You mean, the one that''s up in the sky?
~ Peach having a "blond moment" in Paper Mario:TYD