How to step a pc / computer to monitor internet usage in LAN

Hi
I am new to this system setup. Please guide me in detail.
We have a small office network with windows server 2000 domain
and all computers connected in lan through switch and hub.
we have an internet connection which is connected directly to the router
and this IP address 192.168.45.1 is used in gateway of all computers and internet service providers DNS.Hence everyone is able to browse the internet. Because of this we are unable to monitor the users internet usage and websites accessed by them.

Please suggest how to proceed without using the option internet sharing from another computer.

Can I set up another independent server say windows server 2008 with two NIC such that one points to internal Lan and another to internet.If we join the two domains using trust then we can make use of active directory users from the domain of windows 2000.

In this can we install ccproxy for monitoring the users internet usage.

Please suggest.
Thanks in advance

Yes, ccproxy is the best option to Control bandwidth for your business networks, which can effectively perform the bandwidth control and limit the bandwidth of networks. In fact, CC Proxy Server can also work as monitor bandwidth and create statistics on memory bandwidth.

Thanks for the reply.
I want to know whether instead of connecting to a server for monitoring the users, can I connect a pc not joined to domain and make it a router and specify its ip address in gateway.
Also in ccproxy or any software is it possible to control the no of users logged in to internet irrespective of ip address.Say at a time only 10 users are connected.If any other users say 11th user connects he should not be allowed to browse the internet unless any one user disconnects .This should be automatic.
Please suggest how is this possible?