I came across this article that talks about a nifty tool called MRTG (Multi Router Traffic Grapher). MRTG is a tool to monitor the traffic load on network-links. MRTG generates HTML pages containing graphical images which provide a LIVE visual representation of the traffic.
I've been onsite to companies using this cool tool and it's a great way to watch amd monitor your bandwidth consumption. Best of all... It's free! Well it's freely available under terms of the GNU General Public License. This tool works and operates on Windows, Linux, and yes... even NetWare servers!