Reducing energy consumption is critical to prolonging the battery life in portable devices. With rising energy costs and increases in energy consumption by devices in stationary systems energy expenses of large corporations can annually reach into millions of dollars. Subsequently, energy management has also become important for desktop machines in large scale organizations. While energy management techniques for portable devices can be utilized in stationary systems, they do not consider network resources readily available to stationary workstations. We propose a network-aware energy management mechanism that provides a low-cost solution that can significantly reduce energy consumption in the entire system while maintaining responsiveness of local interactive workloads. The key component of the system is a novel program-context-based bandwidth predictor that accurately predicts application's bandwidth demand for file server/client interaction. Our dynamic mechanisms reduce the decision delay before the disk is spun-up, reduce the number of erroneous spin-ups in local workstations, decrease the network bandwidth, and reduce the energy consumption of individual drives.