Later in the year, Microsoft quietly debuted Windows Genuine Advantage, pitching the downloadable tool as a way for consumers to double-check whether their copy of Windows was genuine. At the time, there was neither a benefit for those who authenticated their software, nor a penalty for those who didn't.After a few weeks, Microsoft started offering incentives for those who participated in the trial, while still not penalizing those whose copy was found to be illegitimate. Last week, though, Microsoft announced plans to make the program mandatory and prevent anyone with an unauthorized copy from downloading from its site.It's Windows vs. Windows...