NetWorx its a free program gratuit for monitoring your network bandwidth. It can be helpfull for finding and identifying possible network problems.
It monitors all or one of oyur network connections, ethernet or PPP. Also, it can visually and by sound signal a suspicious activity and also can shot down the network and your system-this is very usefull for those long nights of downloading files :)You can set the alarm also when the traffic exccedes a preset limit or when your connexion is down, with theoption to power down your PC.
It has also usefull tools like Ping, Trace route and speed meter. All in all, a good tool.