[Galadriel55]

I think that the history of Tom Bombadil and the King of Angmar give enough evidence that the two are not the sae person. Firstly, Tom is the most ancient living thing alive in ME (Treebeard also claims that). The Angmar King was a human, I think a dark Numenorian. Huans awoke after Noldor came back to ME. Numenor was created after Belleriand was destroyed.
Moreover, how can Tom be the king of Angmar when it's so far from the borders that he drew for himself and that he never crosses?
We know about the deeds of the Nazguls in the south (ie near/in Gondor). Tom would be absent from the Old Forrest for millenium if he was really the Witch King. (there is, however, no concrete evidence as to whether Tom was in his forest at that time).
Furthermore, after Sauron was destroyed and the hobbits and Gandalf were returning home, Gandalf says that he wants to have a chat with Bombadil. Assuming that we all trust Gandalf and that he knows that Bombadil is in his forest, Tom is not the witch-king. If he was, he'd be dead.