[monkkey]

http://support.microsoft.com/kb/818025
Гляньте.
Однако, Evaluation copies of Windows 2003 don't use Activation Key. They expire after 180 days.
Из EULA:
YOUR RIGHT TO USE THE SOFTWARE IS EFFECTIVE FROM THE DATE YOU FIRST INSTALL THE SOFTWARE ON ANY SERVER FOR A PERIOD OF ONE HUNDRED EIGHTY (180) DAYS. THE SOFTWARE IS TIME-SENSITIVE AND WILL NOT FUNCTION UPON EXPIRATION OF THE 180-DAY PERIOD. NOTICE OF EXPIRATION WILL NOT BE GIVEN, SO YOU NEED TO PLAN FOR THE EXPIRATION DATE AND MAKE A COPY OF AND REMOVE YOUR IMPORTANT DATA BEFORE THE EXPIRATION DATE.