Since you've mentioned NetSaint. This is a quote from its website:

For those who have not heard, NetSaint is being renamed to Nagios. You can find the Nagios homepage at http://www.nagios.org. NetSaint is no longer actively being developed - all development is now being put into Nagios.

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Ilya Martynov, ilya@iponweb.net
CTO IPonWEB (UK) Ltd
Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net
Personal website - http://martynov.org