I created a Powershell script that will get all the computers from a certain OU and run GPUpdate /force on these machines. This script uses the Quest Active Directory cmdlets and PsExec.exe. You need to install the Quest cmdlets first. If PsExec doesn’t exist, the script will download it to the c:\tools directory.
When you start the script, you have to enter the FQDN and the OU name:
The script creates a text file with al the computer names in it. This text file will be used with the PsExec.exe command.
You can find the script on poshcode.org