Every Wi-Fi adapter requires you to choose between infrastructure mode (called "access point" mode in some configuration tools) and ad-hoc ("peer to peer") mode. When using a wireless access point or router, set every wireless adapter for infrastructure mode. In this mode, wireless adapters automatically detect and set their WLAN channel number to match the access point (router). Alternatively, set all wireless adapters to use ad hoc mode. When you enable this mode, you'll see a separate setting for channel number. All adapters on your ad hoc wireless LAN need matching channel numbers. Ad-hoc home WLAN configurations work fine in homes with only a few computers situated fairly close to each other. You can also use this configuration as a fallback option if your access point or router breaks more >>
Configuring the Host ComputerAfter you install an 802.11b adapter (such as an Orinoco or Cisco wireless network card) on a computer, Windows XP will automatically detect the card, install drivers, and display an icon in the notification area. (I am using Agere's Orinoco Silver cards to construct the ad hoc wireless network here. Although they have native, in-box support in Windows XP, these cards can be updated with even newer drivers and firmware through Microsoft Update). 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. more >>
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. more >>