Hi!
Reading Mfbrew's comment, I was reminded of a little tale that people may wish to forget.
Many, many years ago, when GUIs were not the standard for private homes and there was diversity in the realm of computers, International Business Machines set out to develop a new computer platform. While preparing their big release, they came upon the problem of what operating system to give to it. While they got an offer from Digital Research Inc. to get a port of their successful operating system CP/M, they also had a promise from a private friend of some high ups in IBM, named Bill Gates, boss of the nearly bancrupt little software company Microsoft. In order to fulfill that promise, Bill Gates got a poorly masked pirate copy of CP/M from another company and renamed it to MS-DOS. Unfortunately for M. Gates, Digital Research had already started legal proceedings against that pirate copy which would have probably spelled the end for this business venture. However, the friends at IBM intervened and negotiated for Digital Research Inc. to drop their charges in exchange for getting a sweet deal with IBM. Unfortunately, no one told Digital Research that the IBM computers with MS-DOS were to be dirt cheap compared to the ones featuring CP/M. And the rest, as you say, is history.
That is at least the version of the story I have heard (I was not involved in the entire process and only read much later about it).
Deathworks
EDIT: Disambiguity.
EDIT: Also note that Windows actually already works on the principle of copying what others design. The task bar, for instance, was originally found on Acorn's Archimedes computers (and I think they were the first ones).