It checks to see if your Windows is authentic during the download, but after its downloaded, you can install it just fine on any computer without it checking authenticity. Its possible the program itself checks for authenticity, but since all of mine are authentic, I wouldn't know. If you aren't running authentic Windows, your probably screwed anyway, since Windows needs multiple updates to be somewhat safe on the internet. Good luck getting the updates if your paranoid about authenticity sniffers.

BTW Microsoft didn't develop the program, but bought it from from a company called <a href="http://www.giantcompany.com/default.htm>Giant. You could always find and download the Giant version if you can't trust Microsoft.