At work recently I ran across one more reason why sysprep is such a valuable tool for the deployment of Win2k and WinXP boxes on a network. If you use an imaging tool such as Ghost to create base images for your deployment, make sure to run sysprep before you save the image. If you don’t use sysprep, you may still be able to add machines (duplicated from your base image) to a domain, however, other problems may occur.
One such problem that we encountered was the registry keys for WindowsUpdate remain the same, even though the operating system SID and GUID keys change when you add the machine to a domain. If the machine is not syspreped, the DomainAccountSid and SusClientId remain the same under HKLMSOFTWAREMicrosoftWindowsCurrentVersionWindowsUpdate .
If you have multiple machines (labs in our case) that were not syspreped, you will need to change this value either manually or by script on each of the offending machines. If not, the WSUS server sees only the last machine you added to the domain and does not report the correct machine values in WSUS computer’s report. WSUS will only update the one machine and all others that used the same image will never be updated.