Configuring your Internet settings to protect your home network through the use of a password should be compulsory, as an unsecured network can put your personal information at risk. This can be done in your Windows XP system by altering your router's settings after configuring your network using the automated wizards in the XP operating system.
Click "Start," open the "Control Panel," click "Network and Internet Connections" and click on "Network Connections."
Open the Network Setup Wizard.
Enter in the details about your home network when prompted, including your network's name, type (wired or wireless), manner of Internet connection and Internet authentication information.
Open your Internet browser and type in the access address for your router. This is typically something like "http://192.168.1.1" and is normally listed on the bottom of your router.
Enter in your router's username and password.
Click on the "Security" tab. Click on the option to use password protection and input in your desired network password.
Reboot the computer to save changes.