Bandwidth Control

Hi, NT People.
A question for the NT expert.
I have a wireless lan and I?m using actually Linux to conect this lan with internet. I?mean, I using Linux as a proxy.-
Actually, I want to return to NT.-
But I need a way to control the bandwidth useof my clients.
I read about Microsoft ISA Server. But I believe that the ISA bandwidth control is only over protocols, not IPs.
I need a bandwidth control that allow me to give to each user (each internal IP) a different bandwidth for each different protocol.
Any Idea ??

Thanks in advance.
Excuse my bad english.

Jorge Rubinich