The World of Forms

Does Plato's perfect abstract realm of ideals actually exist?  I'm skeptical on this higher dimension of existence. We discussed in class that noting everything has a counterpart in the World of Forms, like there is no Ideal iPod.  Instead there would be Ideal forms of the natural components that make up an iPod.  But can't that statement be taken further?  Anything physical, natural or not, breaks down into elements.  There is no Ideal horse, just Ideal carbon atoms.  So Plato's argument that our souls remember seeing an Ideal horse and that allows us to recognize horses is invalid since logically, shouldn't everything physical in the World of Ideas be atoms, something we can't see even today?   But what about the abstract concepts that can't be broken down, like Goodness?  I suppose that better question is: Does Good exist?  It's a subjective term that is varies to great degree with each culture.  But if I argue that Good is subjective, Plato could argue that some cultures don't truly understood Good.  So it's hard to argue away Good and other all of Plato's World of Forms.