IP Address + MAC Address

I am using windows server 2003 + ISA server 2004 and I have more than 50 clients which are increasing day by day.

how is it possible that I want to enter a client’s information as IP address & MAC address manually.

A client should not be able to access internet services until his IP address and MAC address (both) do not match the information entered by me.

Can I do this in ISA or Will I have to install some other software… any way I can use, plz guide me.