How to block internet connectivity on a particular computer using MAC add.

I have set up LAN using windows 2003 server in my office.i am getting internet connectivity on server through one static IP address.I have distributed internet connectivity among 10 computers through private IPs using this server via NAT (Network Address Translation).Now i want to block access internet connectivity on a particular computer using MAC address of this computer (configuration in remote access seting) windows 2003 server.What is the procedure/method to do this mechanism? pl. explain me in details where in windows 2003 server i have to configure settings .Pl. help me

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