You can turn an old computer into a wireless repeater to share an Internet connection over Wi-Fi. However, since computers are not designed to offer routing services, you will be limited to an ad hoc network with Internet connection sharing. That means that you will either need two Wi-Fi cards in the old computer or to have it connected to the router physically with a network cable. Also, since the networking possible with an old computer isn't as sophisticated as what's available through a real router, you won't be able to seamlessly switch between the two wireless networks.
Instructions
1. Establish the connection between the old computer and the Wi-Fi router. This can either be through a network cable or through a second Wi-Fi card.
2. Click "Start" and type "View Network Connections." Press "Enter" and right-click the network connection that is connected to the router with the Internet. Select "Properties" and then click on the "Sharing" tab. Click to put a check in the box next to "Allow Other Network Users to Connect Through this Computer's Internet Connection." Click "OK."
3. Click "Start" and then type "Network and Sharing Center." Press "Enter" and click "Set up a New Connection or Network." Select "Set up a Wireless Ad Hoc (Computer-to-Computer" Network" and click "Next." Select the secondary Wi-Fi card in your computer if you are using two cards. Note, if you have two Wi-Fi cards, do not enter the same network ID as the main network or you can cause other computers to be unable to connect. Step through the wizard to set up the network. Other computers will be able to connect to the Internet through the old computer.
