Like Windows XP, Windows Vista can use hibernation to save battery life. Microsoft tells us that its new operating system does not need to shut down as often as Windows XP so it goes into Sleep mode instead. The hard disk and graphic card shut down but the system memory is still active and drawing power. Hibernation uses even less power and keeps files safe, so it is better for a desktop computer that is turned off at the wall. Read the full article at http://www.computeractive.co.uk/2222668