If you want to unseat the beast. What most users are used to is winblows. Its a fact of life. But if you think about it and know a little bit about the history, you would know that the famous winblows desktop is little more than a rip off of Apples GUI. And lets face it really the majority of the "using" public adores icons and graphics, so in order to overthrow Gates and Company, you must by necessity bow to the market.
And if you know a little bit more about the history, Apple's GIU is a direct ripoff of the paperless office developed by Xerox PARC.
Xerox had no idea what they had when they invented the GUI and mouse, and gave it all away.