Bandwidth monitoring software?

Hi there,

Can anyone suggest free software that will monitor the bandwith usage over my router? I have tried a few freewares, but none of them show for the whole network, only for my computer.

A must is that I can see a graph of the current bandwidth usage, and ideally I would be able to keep track of incoming and outgoing traffic (in terms of amount, not content), perhaps being able to generate reports of highs and lows etc.

Thanks in advance!