How to prevent other LAN users from accessing the Internet through router setting?

I have two house-mates who are using the Internet, connecting directly to the router. One of them is using Toshiba Satellite 100 Windows XP and the other is using an Apple MacBook. The model of my router is Netgear DG834.

Now, the storyline goes from an internal conflict in the house, and hence resulted to me, who’s the admin of the Internet and the one who pays for the Internet every month, deciding that I am going to disable them from using the Internet further.

To do that, I logged in to the settings of my router by typing this 192.168.0.1 on a browser and I did not find a feature that could do that. Disable multiple recipients on the network from accessing the Internet… that I paid for.

Does anybody have any idea how I can do that? If this cannot work, is there any other way? Like using the Command Prompt… explanation, please?

Thanks.