You'll first need to install an 802.11b wireless card in the main computer and configure it as a computer-to-computer (ad hoc) wireless connection.
After you install an 802.11b adapter on a computer, Windows XP will automatically detect the card, install drivers, and display an icon in the notification area.
If the computer is in an environment where other wireless networks are in range, Windows should display a list of available networks automatically. However, if no wireless networks are in range, the wireless connection icon may display a red “X” and may not automatically open a View Wireless Networks window. To open this window, click the icon for the wireless connection.
Do not select an available network at this time if any are displayed in the Available networks listing. If your computer previously connected to a preferred access point, remove all preferred access points. This will ensure that a connection is made only to the ad hoc network that you are trying to configure.
Click the Advanced tab at the top of the window. Select Computer to computer (ad hoc) networks only and clear the Automatically connect to non-preferred networks box if it is selected. This setting, along with removing preferred networks, ensures connection to the ad hoc network only.
Click the Wireless Networks tab again. Under Preferred Networks, click Add. In the Wireless Network Properties dialog box, specify a Network name (SSID). Use any name desired, but be sure to use it to configure all computers. Note that the network type is already marked as a computer-to-computer network and that this cannot be changed since it has already been specified that a connection should be made to only ad hoc networks.
After configuring the network name (SSID) in the Wireless Network Properties dialog box, the new ad hoc network will be displayed with a PC Card icon to designate that this is a computer-to-computer network.