Ever make a type-o, i'm sure you have, if you're unfortunate enough to have done this on your windows installation but still have it install, you will notice that very quickly you are reminded of fraud, or asked to activate over and over, a quick fix will let you put the key in again:
1) change the registry key at path: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\wpaevents
key name: OOBETimer
-By double clicking, just replace a letter or number, this will de-activate your windows so you can change the key.
2) open the key changer:
start\run type %systemroot%\system32\oobe\msoobe.exe /a
click the telephone customer support
click change product key
3) Enter your product key carefully:
then click update
*you will be returned to the previous screen and click the remind me later option
this will re-activate your windows and fix your registry key, and if the key is an actual key, that is not already in use (as it's supposed to be) you will now be able to get updates without the above.