Looking for a light network monitor that will email me when a node goes down

[LBP]

I have access points, servers, clients throughout my internal network that I'd like to monitor with some sort of application that will email me in the event any of them go down. Can anybody recommend something that's light, runs on Windows 7 and can be minimized to the systray (not required, but preferred)? Essentially, I'd like it to have a light GUI like Microsoft Excel or Filezilla FTP client, etc… or something similar to the below. Also, freeware/donations or one-time payment is required... nothing that's a subscription base. Thanks in advance for any help on this.

EDIT: Also, I looked into Prtg, domotz, smokeping & flingbox. They didn't look ideal for what I'm trying to find.

[KOM]

I use Zabbix for serious monitoring.  Simple monitoring can be done with a small util called CheckHost:

http://www.ab-tools.com/en/software/checkhostpro/

You can run it for free, but the Pro version has more features.

[LBP]

Check Host Pro worked great. Thank you for the suggestion.

[KOM]

I used to use it in conjunction with Nircmd's speech function to get it to tell me audibly when something is down.

http://www.nirsoft.net/utils/nircmd.html

CheckHost "When no longer available", Start Program: C:\Users\Me\My Utils\CheckHost\FluentStream_Down.bat

FluentStream_Down.bat:

C:\Users\Me\Software\NirCmd\nircmd.exe speak text "FluentStream is not responding" 0 100