After text-mode or GUI-mode Setup completes, a message states that the computer will reboot in 15 seconds. You can edit the WaitforReboot value in the[Unattended] section of your Sysprep.inf (or add the following line to the [Unattended] section:
WaitForReboot=No
BTW, this only workes if your UnattendedMode is set to FullUnattended
