Based on our customer request to find magical and preferably zero cost solution (we get those a lot) we came across freeware utility called ISP Monitor developed by Belgium company How2Solutions.
Unlike NetStat Live by AnalogX or NetFlow Analizer by SolarWinds, ISP Monitor is not the most visually appealing software... However, we have founded it to be easy to setup and understand, it's stable and easy on the system resources, and also functional, highly customizable software with lots of surprising and useful features.
What has really sold us was how well ISP Monitor integrated into multihomed Microsoft Windows 2003 server - we only needed to physically select interface we wanted to monitor, and we were done...
ISP Monitor will monitor and report your total, upload/download bandwidth in real time as well as save daily logs you can show in the main window. You can also specify your account bandwidth limits and trigger warnings, email alerts, and even cut-off your network connection altogether.
As we have mentioned ISP Monitor is FREE... However, it has a few premium features designed to give you some extra functionality and integration with certain European telecoms and ISPs.
For more information, support and latest version of ISP Monitor visit ispmonitor.be.