Once we introduced Windows 7 systems to our network, our GPO to set the screensaver and lock the system after 15 minutes stopped working.
A Google search only relevantly led me here:
So after some leg work, here is the GPO you want to create & use now.
Create a GPO Link and set it up as follows:
Let GPO replicate or gpupdate /force it.
Tested on Windows 2003, XP, 2008 & 2008 R2 & 7. Not tested on Vista, assume it’ll work.
If you want more granular control you can create WMI filters. This nice article Creating WMI and Group Filters for 2000, XP, 2003, 2008, Vista, 7, 2008 R2 is right from the documentation gods @ Microsoft!