uptime solution

[Mark McCulligh]

On the topic of uptime, what is the best way to track your connection 
uptime.  With a generator/UPS you can have a computer running 365 days a 
year, but your ISP/Network may not have the same uptime.  Is there an 
open source package to track your overall uptime of your web server.  I 
know there are companies like Vertain you can pay to ping your server 
and give you uptime reports.

Mark.