A method and system for providing system event notifications to clients such as applications. Clients register for notification of one or more types of events with a registration mechanism, and a System Event Notification Service, (SENS), receives system event information and fires event notifications in response thereto. A distribution mechanism selectively communicates the fired event to each client registered for notification thereof based on the type of event. Events include network events, for which the service monitors the connectivity state of the machine, including whether a connection is established or lost, the type of connection (LAN/WAN) and bandwidth information. To monitor a LAN state, the service caches outgoing and incoming network information including errors and packet counts and statistically evaluates this cached information against current information to determine whether the connection is established or lost. The service also determines if a destination (IP address or name) is reachable, by periodically polling destinations. Other system event notifications may be fired, including logon or logoff operations and power management events.