I have created a GPO to hide the notification area on Windows XP SP3. The GPO must apply to all students but only in certain rooms so I've also enabled loopback processing on the GPO and linked to the OUs the computers are in. I've then added a group to the security filter that contains all student accounts.

This is not applying. It doesn't even show up in gpresult. I have also tried linking it in the Students OU which contains all student accounts and applying a security filter with a group of the computers I want it to apply to. This didn't work either. It's possible I'm missing something straightforward.

Would a WMI filter do the job, and if so how would I go about writing one so that it'll only apply to computers whose name begins with XX-RT for example.