Question : Bandwidth Monitoring Tools

Hello All,
I am looking for a tool that will monitor the internet network bandwidth of my users. I'd like to ideally know how much bandwidth they are taking up on my pipe and have a report. If you use anything that is worth while please let me know.

Thank you!

Answer : Bandwidth Monitoring Tools

NTOP as a netflow collector if you have netflow capable router/firewall
or
NTOP on a mirror port of the switch
http://www.ntop.org