There are many SQL Server Events, SQL Performance Condition Alerts, as well as WMI Events that can be set up rather easily under SQL Server Agent >> Alerts.
Settings up these alerts gives you the option to specify a response i.e. (notify a particular operator), and additionally specify if you want to Email, Page, or netsend the event should one occur.
These are free :-P
"Never argue with an idiot; They'll drag you down to their level and beat you with experience" ;-)