Since normal users (or non-admins) are “less powerful” compared to admins, they cannot change the XP power configuration.
You can assign “Create value”, “Create Subkey” and “Delete” rights to the following registry key for the users on your computer:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg
Then normal users are able to adjust the power configuration as well.
