Protections for internet

Hello,



i have 7 computers having wireless card net gear 311 with access point cum router cum modem provided by BSNL having model - ZTE ZXDSL-531B ,i am using all the computer in network and set the broadband connection in dhcp server and provide all of them WPA-PSK (security) . All of them are working fine. Now the problem is that the internet service is used by all the pc's .and I want that only three pc's can use the internet facility. So, tell how can I do this and all proper setting for the access point & pc's

Please help

thank you