WPKG with Active Directory
Below settings for Active Directory - screenshots are in German, but I think anyone who doesn't know German, but saw Active Directory will know what to do:
First, run dsa.msc
Then navigate to the group of computers, and select "Eigenschaften" ("Properties")
Next, select "Gruppenrichtlinie" and select "Bearbeiten"
Next, you have to choose the right settings for the execution of scripts:
Correct settings for script execution
Navigate to Computerkonfiguration -> Administrative Vorlagen -> System -> Skripts. (Computer Configuration -> Administrative Templates -> System -> Scripts)
Make sure that "Startscripts asynchron ausführen" is set to "Aktiviert". (Apply Startup scripts asynchronously is set to activated)
This make sure that the user can log in, even though the software is still being installed. It's a good choice, because some unpatient users will just press Reboot button when they can't log in immediately, which can have unexpected results (software not installed properly etc.).
Next thing to set is setting "Maximale Wartezeit für Gruppenrichtlinienskripts". Default is 600 seconds (10 minutes), which can be often not enough for installing some software, or when you install more than one software package. So a safe bet is 1800 seconds (30 minutes).
Selecting a script
The last thing you have to do, is to select a script which will start WPKG on a system start. This script is located in a batch file:
\\server\path\to\WPKG\wpkg-start.bat
and contains the folowing line which starts WPKG:
cscript \\server\path\to\WPKG\wpkg.js /synchronize /quiet /nonotify
NOTE!
Sometimes a group policy is not applied when it is setup and the workstations are rebooted for the first time. The reason for this is that group policy is pulled from the server by default every ~90 minutes. If you require group policy to take effect immediately, you may run "gpupdate" (XP) or "secedit /refreshpolicy user_policy" and "secedit /refreshpolicy machine_policy" (Win2K) from each workstation.