I'm currently running NSClient++ on Windows SBS 2003 and am having horrendous problems with time-outs from Nagios3 generating a load of warnings, etc.
I'm pretty sure that the errors are caused by load spikes on the SBS as, from time to time, we've had issues with Outlook connectivity as well.
Please bear in mind that reconfiguring / upgrading or generally doing anything drastic on the SBS is not an option as it's the core of the business and works, granted not very quickly but it works.
Are there alternatives to NSClient++ that work reliably and securely on Windows? Is SNMP an option? If there anything I should look at on the server side?