Monitoring internet usage in multiple computer household

[lycans]

Hi all,

Is there a way to monitor internet bandwith usage for each individual users in a house? I am currently in Australia where 'unlimited internet' doesnt exist, we get 40 gig of internet bandwith and if we exceed that the speed gets reset to 56k and some idiot in my house is sucking up so much bandwith that its impossible to last through the month. I want to know if there is any commercially available program that I can use to monitor who is the bandwith bandit in my house.

Thanks in advance

[liangtam]

Install software on each and every PC lor.
If this is not possible, then no for general consumer solutions.