As Microsoft steps up its war against piracy, the company has decided to slightly nuance Windows Genuine Advantage (WGA). Rather than identify users as either in the clear or not, the company has added a third classification for users who set off some, but not all of WGA’s undisclosed piracy-detection functionality. Users will now find that Windows XP installs are labeled as genuine, non-genuine or “not sure.”
It seems unknown right now what exactly will happen if you receive the “not sure”, but it doesn’t appear as though you will see the foolish “Non-Genuine” messages.
Source: Ars Technica