Sysprep has just become easier in Windows Server 2008 R2. The sysprep file is now already preinstalled by default. You can find it in Windows\System32\Sysprep.
Just launch the Sysprep application in this folder, check the Generalize check box, select Shutdown, and after the machine has shut down you can use it as a base image.
After reboot the well known Windows mini setup will start.