what is the point of this ... you know if your windows is genuine or not, you bought it on a trusted reseller, so it is genuine. You downloaded it from a warez site, it is a pirated one, and in that case you know how to make it "genuine"
the only way you get fooled is when buying a new PC with it preinstalled.
Yes and No, when you got a pirated Windows, you got only the important updates; but sometimes an update notify you at the reboot that your copy is fake and it disable your wallpaper and put a permanent notification at the bottom right of your screen. This notifications can be easily overcomed.
If you're a student in the US you can probably get it for an incredibly cheap amount if not free. I got mine for 20 dollars and I know others who have gotten theirs for free.