A method for determining the location of a client computer, the client computer having an existing wireless communication session with a wireless access point of a computer network, the method comprising: measuring the strength of signals received from a plurality of wireless access points of the computer network, including the wireless access point to which the client computer has established the existing wireless communication session, wherein each wireless access point is located at one of a plurality of locations, and each of the plurality of locations has one or more of the plurality of wireless access points; repeating the measuring step to obtain a plurality of signal strength values from each of the plurality of wireless access characterised by: calculating the difference between each signal strength value and a threshold value to obtain a plurality of modified signal strength values for each of the plurality of wireless access points; weighting the modified signal strength value for the wireless access point with which the client computer has established the existing wireless communication session; weighing each modified signal strength value such that the more time that has elapsed since the signal strength value was measured, the less weight the modified signal strength value receives; averaging the modified and weighted signal strength sample values for one or more wireless access points of each of the plurality of locations to obtain a plurality of averaged values, each of the plurality of averaged values corresponding to a location of the plurality of locations; summing modified, weighted and averaged signal strength values calculated from the signal strength values obtained from the measurements at different times; determining which of the plurality of weighted and averaged values is the highest; and designating the client computer to be located in the location for which the averaged and weighted value is determined to be the highest. measuring the strength of signals received from a plurality of wireless access points of the computer network, including the wireless access point to which the client computer has established the existing wireless communication session, wherein each wireless access point is located at one of a plurality of locations, and each of the plurality of locations has one or more of the plurality of wireless access points; repeating the measuring step to obtain a plurality of signal strength values from each of the plurality of wireless access characterised by: calculating the difference between each signal strength value and a threshold value to obtain a plurality of modified signal strength values for each of the plurality of wireless access points; weighting the modified signal strength value for the wireless access point with which the client computer has established the existing wireless communication session; weighing each modified signal strength value such that the more time that has elapsed since the signal strength value was measured, the less weight the modified signal strength value receives; averaging the modified and weighted signal strength sample values for one or more wireless access points of each of the plurality of locations to obtain a plurality of averaged values, each of the plurality of averaged values corresponding to a location of the plurality of locations; summing modified, weighted and averaged signal strength values calculated from the signal strength values obtained from the measurements at different times; determining which of the plurality of weighted and averaged values is the highest; and designating the client computer to be located in the location for which the averaged and weighted value is determined to be the highest. calculating the difference between each signal strength value and a threshold value to obtain a plurality of modified signal strength values for each of the plurality of wireless access points; weighting the modified signal strength value for the wireless access point with which the client computer has established the existing wireless communication session; weighing each modified signal strength value such that the more time that has elapsed since the signal strength value was measured, the less weight the modified signal strength value receives; averaging the modified and weighted signal strength sample values for one or more wireless access points of each of the plurality of locations to obtain a plurality of averaged values, each of the plurality of averaged values corresponding to a location of the plurality of locations; summing modified, weighted and averaged signal strength values calculated from the signal strength values obtained from the measurements at different times; determining which of the plurality of weighted and averaged values is the highest; and designating the client computer to be located in the location for which the averaged and weighted value is determined to be the highest.