Web Monitoring Tool Sql

Hi
i am looking to build a web based monitoring tool
I have a few server in different sites and I need to monitor them.
What I have come up with is using a web application

I have Sql2005 server on 5 sites
I want to make sure that they are always up and back up is working.
Also want to make sure certain service are running.

So when something goes wrong on the server I will be emailed asap so I can investigate the problem

Ta
Gerard