Microsoft has argued that you buy a LICENSE to use their software, not the physical software itself and that you have no right of resale.
MS even used to shut down ebay sales of SEALED software if it came bundled with a computer and you are not an authorized vendor for the software title.
Bill Gates apparently doesn’t have enough money even though he insists that death panels are a good idea for the peons and that “you” aren’t paying enough taxes.
The thing about Microsoft and their software.
It is my understanding that you buy/license the OS, but can use it on different PCs, but not at the same time.
So, if you bought a PC with Windows* and that machine crashes, you can reload the OS to a new/different machine.
Since most PCs come with the Microsoft OS preloaded, they have a sticker on the box with the registration/license code. You can pick up an old or inoperable PC pretty cheap, much less than the cost to buy the OS as a stand alone program.
So, if you need a new/newer or a version of Microsoft’s OS, you may want to look at buying a used machine.