Configuring Nagios
I followed the guide provided by http://www.myelin.co.nz/post/2008/10/30/#200810301 . I successfully confgiured Nagios on a system. The toughest job was to put all the hosts on the hosts.cfg file in the nagios3/conf.d/
I had manually enter all the 150 odd local ip's in the file. Then success came fast then expected. i was seeing screen which filled my heart with happiness. Nagios is a perfect package for remotely monitoring clients.

I also consulted some guys on irc chat who specified to use these tools for remotely running shell scripts on clients :
1. DSH
2. PyDSH
3. Puppet
4. CFengine
5. Fai-server
If time allows, i would explore the above mentioned and put them in my blog. Or may be i would unlock the ssh feature in Nagios itself.