How to share the internet between 2 puters w/ one modem??

I just had Comcast set up cable internet in my house. They gave me a black modem and the internet does work on ONE computer but I need it to work on 2 computers in the same room. One computer is running XP and the other runs Windows 7. How can I set up the internet so both computers are online at the same time??? :confused

 

You need to get what is called a router . . . they are fairly inexpensive and can be had at most department stores.

I recommend Linksys or D-link products for ease of set up, but there are many makes and models to choose from, such as listed here:

http://www.directron.com/routers.html

You can also do internet connection sharing between the two PC's - one of the PC's would need two network connections (such as an add-in PCI network card), and serve as the Gateway computer. For ease of set up I recommend using a router, which also provides a hardware firewall to protect your LANed computers.