To tell your computer which Wifi network to connect to if using Windows XP, click on the wireless network icon in the Taskbar’s Notification Area, then click the Properties button. (If the icon is not there, press Start, choose Control Panel, double-click Network Connections, then double-click the Wireless Network Connection icon and click Properties). Select the Wireless Networks tab. All known wireless networks are listed in the Preferred Networks box. Click on the names and use the Move Up or Move Down buttons to rearrange the list, putting the preferred network(s) at the top. Networks can also be removed from the list using the Remove button. Click OK, then Close when done.
In Windows 7, the wireless network icon is also in the Notification Area, but looks like a triangle with vertical bars. Click on this and click the link labelled Open Network and Sharing Center. Click on the link labelled Manage Wireless Networks at the top left side of the window. A list of known wireless networks will appear (note that this doesn’t show currently available networks - just those that have been used in the past). Highlight an item and use the Move Up and Move Down buttons to rearrange the order that Windows tries to connect to the networks.
The procedure for Windows Vista is almost identical, although the network icon in the Taskbar is different again, and looks like two small TVs with a globe superimposed. Click on this, then click the Network and Sharing Center link. In the left of the window is the Tasks list. Choose Manage Wireless Networks and follow the instruction for Windows 7 (see Step 2). In Windows 7 and Vista, as well as using the buttons, right-clicking on a network name shows the Move Up and Move Down commands on the context menu.