ZT3000 does make a good point. But right now the OBVIOUS problem is the hardware is not up to par for the work load. Monitoring the network will be MUCH easier once it is segmented correctly and you have proper hardware in place. One that is done you can drop a sniffer box on the network somewhere and monitor each vlan on its own (I said this all in my first reply BTW) Networking monitoring and policy management is a beast on its own, and changing the hardware is far from just a bandaid. Its a pain to use unmanages switches and hubs if you really want to do GOOD monitoring. especially in set up where everything is in one domain. You cant control nearly as much and you cant fix a problem when it is found nearly as easily.

I do fully agree that the company should do a full network analysis/audit before dropping this kind of cash. that way you can get an optimum solution for the problem rather than a generic one.