When Personal Computers are networked, energy consumption increases due to the direct requirements of the PC network interface and network infrastructure hardware (switches, routers), as wall as indirectly by keeping many PCs in a higher power state than is otherwise necessary.  The size of this increase is already large, and poised to increase with more network-dependent applications being used, and more non-PC devices gaining network connectivity.  This talk will review the size of the energy impact from networks, mechanisms for power management in PCs, technical opportunities for reducing the induced and direct energy use, and the potential energy savings. This topic is important in its own right, but also indicative of a new type of energy problem/opportunity that is likely to become more important in future as energy use is increasingly connected to electronics and digital networking.