1. A method of managing the power distribution for a portable device, which comprises: (a) categorizing each task to be executed on the portable device; (b) prescribing a power management policy; (c) based on the power management policy, allocating a predetermined ratio of a unit power supply to each task according to a category of which each task is associated therewith; and (d) increasing the share of the unit power supply allocated to a task running in an active window according to the commands entered through a graphical user interface.