... tell pirates to pirate other people's software? They already have WGA which they seem certain is capable of identifying systems running pirated software. Why not take it a step further and tell the pirates to use some other operating system? There are plenty of good alternatives whose creators would love to have people pirate more often:
Honestly, if Microsoft does not want people using their software without paying, it would go long way toward stopping that if they were to send their pirates elsewhere. If they do not want to do that, they could start distributing Windows for free like Canonical distributes Ubuntu, although I imagine that would defeat the purpose of trying to convince people that only those who give Microsoft money should use Windows.