Network Audit software

Is there such a thing as a piece of software that will permanently monitor your network for machines with shared drives, open ports etc?

I have been using Project R3x to keep an eye on my network since Bugbear arrived, but it will only show those machines which are on when it tries to analyse that particular IP address.

What I need is something that will keep a record of which PCs have shares, etc even if the machine has been switched off, or has been switched on since the software started analysing.

Can anyone help?

I'm sure there is something like that out there. Although, I wouldn't be surprised if congestion on the network increased by a lot while running a tool of this nature. Have you tried a Google on network monitoring? Don't underestimate the power of a Google. ;) Nothing comes to mind right away, but I will let you know if I come up with anything good.