How to Convert a Desktop Computer to WiFi
Converting your desktop PC system into a Wi-Fi enabled system is a fairly simple process. With this method, you will be able to receive a wireless connection to your computer, enabling access to the Internet through your currently connected DSL or broadband connection in your home or office.
Locate the power cord in the back of the DSL or cable modem, and disconnect it from the power source.
Locate the ethernet or USB cable currently connecting your cable or DSL modem to your computer. If you are using an ethernet cable, it should look similar to an over-sized telephone cord. Disconnect the end that is currently connected to your computer.
Look at the back of your wireless router. There should be a single ethernet port (LINE IN), and then 4 LAN ports (LINE OUT). Connect the ethernet cable to the single ethernet port (LINE IN).
Connect the power to the modem, and wait at least 30 seconds for the connection to reset, and for the lights to have stopped blinking. Connect the power to the wireless router, and wait another 30 seconds.
Connect the wireless adapter to any available USB port on your computer. If you are running Windows XP or higher, your computer should automatically detect your connection, but you may also need to install any software that came with your wireless adapter or router.
To connect to the wireless network, open Network Connections from the Control Panel. Right click the network connection you wish to use (in this case, Wireless Network Connection). Click "Connect" from the pop-up menu, and Windows will connect you to the network, enabling your wireless connection.