Sharing libraries between multiple computers requires having an exact copy of your library set on all computers. All of the custom library information you create can be found in your custom folder which is found in one of the two locations listed below.
XP C:\Documents and Settings\All Users\Application Data\PCB123\Lib\Custom
In this folder you will find three different file types.
.slb = footprint libraries
.sym = symbol libraries
.tax = taxonomy entries
Please contact customer support if you have any questions.