Sysprep prepares a computer for disk imaging or delivery to a customer by configuring the computer to create a new computer security identifier (SID) when the computer is restarted. In addition, Sysprep cleans up user- and computer-specific settings and data that must not be copied to a destination computer.

Sysprep.exe utility is a part of Windows Server 2008 and it is located in %windir%\system32\sysprep folder (in our case it is c:\windows\system32\sysprep).

You can find more information about Sysprep utlity here: http://technet.microsoft.com/en-us/library/cc766049.aspx