Measure internet usage on AD network

I have a Active Directory based network (Win2k3 server, WinXPPro Clients) on a DSL connection.

I want to setup some way of measuring the internet usage of each user on my network. I thought I could put a RouterBoard device between my network and DSL router, and then somehow get the RouterBoard to track the internet usage of each user, so that I can then create reports for managers showing the usage for a given time period.

Is this possible, and if so, what techniques / methods can I user to acheive this?

Look up Traffic Flow on the wiki. It’s equivalent to Cisco’s NetFlow. There’s free analyzer tools available.