Waspnest is a website monitoring program that runs as a service under Windows XP. It will send an email notification if a monitored URL is offline. A local SMTP server is not required. It uses sockets to communicate with the target SMTP server.
Monitoring tool with support to Websites, RSS, Webservices and Databases. Has notifications by email and RSS and you can access metrics like availability, latency and load time by a web-based GUI. Runs standalone with an embedded HTTP server.