SmartPower is particularly suited to Windows Home Servers, torrent or download boxes, and HTPCs. SmartPower is a Windows service that saves energy by hibernating and resuming your Windows PC according to configurable rules. The SmartPower configuration utility lets you create rules that prevent this happening. When SmartPower sees that no rules currently apply it will initiate hibernate (or suspend, or shutdown).
What's new in this version:
Version 1.5.6 added another power plan check for "hibernate after" setting.