Large IT shops use enterprise-class network and application monitoring on a daily basis. Implementations of suites such as HP OpenView, CA, and others can run in to hundreds of thousands of dollars and required expert knowledge. While it will meet your every need, smaller shops typically cannot afford this kind of investment.
There are also many mid-sized IT management applications targeted toward the MSP model. Kaseya is one that is excellent. There are also strong offerings from Microsoft.
However, what can you do if you have zero budget? Its time to turn to Open Source…
Nagios is an enterprise-class network and application monitoring solution that runs on various Linux platforms and Apache webserver. Installation and configuration, while well documented, will be challenging for novice Linux users. However, once installed and working, this package will cover your needs out of the box. If not, there is a large community developing plugins of every flavor, including environmental monitoring device support. Nagios also has hooks that can be connected to other packages suck as Splunk for advanced indexing, search, etc.
Nagios runs very well in a virtualized environment, just one more reason to check it out (no need for additional server hardware!).