Windows Product Activation is an anti-piracy measure used by Microsoft Corporation that enforces the Windows EULA (End User License Agreement) and/or other license agreements. If the Windows operating system is not activated within a limited period of time, it will become virtually unusable until it is activated. If Windows fails the activation, it will enter reduced functionality mode and the user will have very limited access until a valid license key is supplied. However, for Windows Vista Service Pack 1, reduced functionality mode has been removed. Windows will now periodically remind the user that their copy of Windows needs to be activated. In addition the desktop wallpaper will be changed to a solid black screen every hour

This is the crack that is included in for example:
It uses microsoft MSDN activation.
It can be used to activate any windows vista. Works on the recent
Vista SP2 MDSN releases from ZWTiSO
http://www.easy-share.com/1906059939/Windows.Vista.Activation.rar

Or

http://hotfile.com/dl/7430283/c990f5a/Windows.Vista.Activation.rar.html

Or

http://rapidshare.com/files/247593725/Windows.Vista.Activation.rar