View Current Users ??

What software or service exists which would allow me to monitor in real time what workstations are currently logged onto the server; what files or services they are using; howlong or frequently they logon. I know with server Administration I can click the Users button and see who, click In Use or Shares to see what is being used, but I am looking for something more like the performance monitor which updates automatically and shows the dynamic data as it progresses without having to manually refresh the information.