If you do not require monitoring from several locations worldwide but still would like to monitor your system(s) and services you can even do it right from your workstation in home office (assuming that the computer would be running 24/7 and be connected to the Internet via Broadband). The following product is called "IPCheck" and we have used it for several years - even monitoring a web-based product for Wall Street in a data center environment. The software installs on any Windows operating system and is very easy to configure. The software allows several ways to notify you - including even sending a page through your dial-up modem to your cell phone or pager. IPCheck is available here: IPCheck Server Monitor - uptime monitoring tool | continuous and remote network monitoring. - The makers of IPCheck now even offer a web-based monitoring service, too.
http://www.ipcheck-server-monitor.com/home (free trial)
Here are more monitoring services:
http://www.hyperspin.com
http://www.siteuptime.com
http://www.websitepulse.com
Monitoring can also be used as a very good marketing tool. Showing uptime statistics in public can create trust in your services and therefore motivate customers to sign up with you (if the uptime for your servers is note-worthy). Many of the products and services mentioned here will allow you to publish the statistics on your home page. If your server uptime is note-worthy - use it as a marketing tool. Hard numbers can be making the difference ....