(V): '"windows" is not a Microsoft idea' : Windows is a valid MS product unless a court decides otherwise. The fact that the Mac OS was there before is immaterial, since Apple did not act on it. If there was a copyright infringement we would heve heard about it a long time ago.

'the customer has to buy a windows disk' : Well no, not in France, anyway. If you buy at a second hand shop a PC without a disc you can easily buy a new clean disc and install on it whatever you like: A MS product (Windows, presumably) which you can buy at a store for a certain amount of $$; or easily find a free, perfectly legal non-MS operating system, which you may or may not know how to operate. The third option, which is slightly illegal, is to install an unpayed MS product - at your own risk.