I must emit this whole windows activation process is extremely complicated. The issue I want to address, namely, is how does Microsoft know that my COA key is valid or not, or more precisely, know that my installation hasn't been licensed more than is allowed? Is my COA key a totally unique key? Let me invent a scenario. I custom-build a computer, so obviously it's not a royalty machine, and I seperately buy a legal copy of windows xp professional. During the setup/activation process I must provide my COA key. Unfortunately, somewhere out in cyber space, someone has used an illegal keygenerator to generate a key, which just *happens* to be the same as my COA key. Now, what does microsoft do and how do they handle situations like this without preventing thousands of legitimate products activate?