Recommendations on Server Monitoring and Alerts

Hi Guys

Looking for a solution for a remote site with only one IT Guy,

They have 5 Servers,firewall,numerous switches,exchange,sql server,etc

Im looking for a package to sit on a server \ desktop to monitor the status of all this equipment.

Simple things like server disk space,power failures \ warnings from ups,Sql Server checks,Exchange,etc

Previously used Servers Alive in another site and this worked well as we could send sms alerts in case of a serious problem.

Anyone recommend Servers alive or else any other package ?

Thanks

Rob