This section is in Spanish. You can monitor activity using a Keylogger, most of them are detected as trojans by a lot of antivirus but you can add an exception to detection list so it do not show as a menace.
The free tool is Revealer Keylogger, it's free and it's easy to use, although you need to have physical access to retreive the data. Good luck.

Enabling remote administration and administrator user in the target computer, you can use event viewer from anywhere in the local network. It's a computer's log of the activity. Simple.

You can use any keylogger, but be carefull becose can be detected as a virus.

with a remote desktop server

What kind of monitorin?
Remote monitiring in the local network? VNC
Monitoring a computer outside the office? Better install a keylogger. The check the activity.