0ld animated movie in which I remember a boy working in big tower or something... washing dishes and all and then there is this good old man who knows magic... and magic helps the boy to work... something like that... but I am not able to get the name?

If the old man was Merlin the magician
And the boy was Arthur

Sounds like,.

The Sword in the Stone (63)

-view clip- (http://www.youtube.com/watch?v=75BJ2ovo-S0)