1. A computer system having a power-down mode to conserve energy, comprising: a speech transducer for capturing speech; a low power wake-up indicator coupled to said speech transducer, said wake-up indicator detecting speech directed at said speech transducer and asserting a wake-up signal to a powered-down processor, the low power wake-up indicator having a low pass filter and a power comparator coupled to the low pass filter; and a voice recognizer coupled to said speech transducer and said wake-up signal, said voice recognizer waking up from the power-down mode when said wake-up signal is asserted.