Microsoft has been quietly slipping in WGA-like checks like
KB971033 amongst the many updates in Windows Update. However, these
initial anti-piracy checks are voluntary in basis. In fact, they even
unchecked it by default. You can even "disable it" permanently by
hiding the update.
Even so, it was only a matter of time before Microsoft makes one of
these anti-piracy updates mandatory. Normally, a mandatory anti-piracy
check would be introduced when a service pack is scheduled to appear.
You will need to submit to this anti-piracy check and pass it before
you are allowed to install the service pack and gain access to future
We think that Microsoft has just introduced a mandatory anti-piracy
update - KB976902.
Read more at TechARP.