For W’2003 server….
Click Control Panel > Administrative Tool and navigate to Local Policies & click “Audit Policy”. Now to monitor user’s activities to terminal services, just double-click “Terminal Services”. On next dialog box, select Enabled from policy value box. Again, click OK to save the settings. It can be also done through remote control option in tsadmin (an exe ) / use shadow the command line.
For W’2008 server, you may use Windows System Resource Manager / WSRM.