I've yet to see any copy protected OS.... tends to be kill sales if you cant even install the OS needed to install the protected application :-)
That said, ever notice that copy protected commercial applications are the exception, and not the norm. Go back to the 80's, and many were, but these started to become rarer by the 90's... I guess developers realised that the cost of licencing protection outweighed the benefit (especially in a low volume market), key disk could be duplicted on a different computer (mig was good for that <grin>), and sector referencing was often buggered by defraggers (tho BT was still using it a couple years ago). Arise, Sir Dongle (until they were cracked or the app source code was compromised), and serials --- arise s2k :-)
yet still publishing houses licence secureROM, safedisk, et al... at god knows what cost per title... despite the popularity of -nocd and -fixedexe from gamecopyworld....