Pirated Software

BBC's coverage on pirated software is pretty good, but copyrights are really unmoral. You can't share your Windows XP installation disk with your neighbour, which is bad enough. What's good when you can't share it? When you buy a software, you actually buy the permission to use it, but not to modify/change/redistrubute it. So whats' the use of Windows XP if you don't actually buy it? You don't even own it. Then what's the use of buying software?