WGA notification tool... why?

Much to my dislike, there's still some software which doesn't work yet with Linux, either natively or using the fabulous Wine, so for those cases where I still need to use win32 software, I use VirtualBox and a virtual machine running Windows XP.

My copy of XP is registered; I payed for it simply to avoid getting all those annoying warnings and various disgusting issues one can run into when using a pirated version of XP.

But still I get this idiotic update from time to time:

WGA

The Windows Genuine Advantage Notification tool notifies you if your copy of Windows is not genuine. If your system is found to be non-genuine, the tool will help you obtain a licensed copy of Windows.

Do they mean that this already genuine copy is going to turn into non genuine, just like that? Ta-daaaaaaaaaa! today I'm genuine, tomorrow I'm not? surprise! And that's why they need to check every month? Didn't they check the first time I entered my serial number?

Most probably they fear someone buying a license and then installing it in several other computers, but this way of fighting their fear is stupid. Just leave alone the nice chaps that installed and registered this weapon of mass destruction and go annoy people who haven't completed your verification process or however it is called at this time.

Whenever someone asks me why I don't want to use Windows again unless it's caged on a (virtual) box, I'm so going to refer them to this!