1. A method of employing a computer in optimizing the timing of a number of maintenance activities that relate to a number of elements of a facility, the method comprising: for each maintenance activity, employing the computer in: determining a number of failure probabilities of an element based upon an assumption of performance of the maintenance activity at a given time, employing at least some of the number of failure probabilities in determining a number of changes in probability of failure of the element based upon the assumption of performance of the maintenance activity at the given time, and employing at least some of the number of changes in probability of failure in calculating a number of expected net savings based upon the assumption of performance of the maintenance activity at the given time; employing the computer in performing said determining, employing, and calculating for each of a number of assumed given times of performance of the maintenance activity; for each of at least some of the maintenance activities, employing the computer in determining the given time at which the corresponding expected net savings result in a substantially maximum net present value; and outputting from the computer a plan for the proactive performance of a number of the maintenance activities that is based at least in part upon said determining the given time.