Just say somebody uses a imaging program to image a copy of XP PRo and burn it to a disc. Using a slow read and write speed to improve reliability of the disc. It doenst have any missing files, or problems. Its just like a normal copy of XP except you cant update it and Microsoft might get angry.
A pirated copy is exactly the same as a real version, all that's happened is a CD has been read, and the contents reproduced exactly onto another CD. So the two copies are exactly the same, content wise. If the same CD key is used, then Microsoft can only assume that the same person is vising the update site for some reason.
XP is worth it but you don't need to get the cd.. all you need a a valid key.... Just order a key online with out media, easy to find on price watch.... Then borrow an xp home or pro cd from a friend and load up all good to go...