Neither will do that. What you want is an NMS, like OpenView, OpenNMS, Nagios, Big Brother, etc. If you want immediate notification, you can use an SNMP trap receiver built into the NMS, or use syslog and a log watcher.
You can monitor when an user loses connectivity, but remember that the user turning off or rebooting the computer will also cause a notification. I'd just monitor the servers and key interfaces of the network devices.