monitoring pc by network

my pc connected to the network in the office through LAN connection. I use other pc to store my files so my friend could collect the file from it (share folder in other PC).
I need a program/software so I could monitor my PC or other PC (that I used as store pc), if any user has collecting data from the store pc without my permit, or any user who try and has collect data from my own pc.
is there any software like atelierwebremotecommander, that I can monitor other pc or user from my pc.