Standby/Hibernation

I have recently setup 125 Dell GX280 running XP w/SP2
which came pre-installed by Dell, the problem that I am having is all the systems go in standby after 10 mins, I have gone in under local Admin & Domain Admin and disabled it under power but it only makes changes on those accounts. Is there a way to disable it so that affect every user? I don’t want to have to go to each machine and do this…a regedit maybe?