Like many of the disney movies that came from fairy tales the basic story of Snow White isn't copyrighted, but some elements you'd expect in a Snow White story were added by Disney and are protected. The biggest one is the names and personalities given to the seven dwarfs (happy, grumpy, doc, etc). If you made your own snow white movie and included those characters or had them singing "Heigh-Ho" you could expect to get sued into bankruptcy by disney lawyers.