Connecting to internet with dial xp machine

Guys I have 3 machines at home, all my machines are running windows xp service pack 2, all my machines are on the same network by way of an 8 port switch.

One of these machine is dialing to my ISP for internet connectivity, what i need to do is be able to browse the internet from the other two machines using the existing connection to the ISP without moving the modem from one machine to the next. please help me

Thanks in anticipation