Yes, but do not start HostMonitor as interactive service (application can hung). In the case you really need to start HostMonitor as a service on Windows NT 4.0, please, disable the "allow service to interact with desktop" option in the Service Manager (after service is installed).
You will not be able to see HostMonitor's icon in the system tray. To configure the program you will need to stop service, start HostMonitor as a regular application, change the settings and restart the HostMonitor service. On Windows 2000/XP systems HostMonitor can work as interactive service without problem.