If you have Pro, click "start" then click "run" when the run command comes up, type "compmgmt.msc" when the program comes up, look down the left and expand the "local users and groups" part, then double click on power user and click the "add" button, in there type your brothers username and add it to that group and you should also find his account one of the other areas and make sure he is removed from the administrator group
