From The Cadmus Group:
ENERGY STAR's EZ GPO tool allows a network administrator to centrally control power management settings using Group Policy Objects (GPOs), saving up to $50 per computer per year in energy costs. EZ GPO can also activate 'system standby', which places the PC box to sleep, uses the existing functionality on Windows 2000 and XP, and does not require special hardware or network processes. It is designed for network administrators who manage Windows client workstations using GPOs under Active Directory. Unfortunately, much of a computer's energy is needlessly expended as the computer sits idle, perhaps while you are in a meeting, on the telephone, or at lunch. Fortunately, we can reduce this waste through the use of EZ GPO, which can turn off your monitor, a computer's most consuming component, during idle time. To easily activate the ENERGY STAR capabilities of your network, run EZ GPO. After several questions, the program will turn on the ENERGY STAR features that works with your monitor.