Secure your wireless network - Easy tips from Kim Komando
This is excellent and easy to follow in securing a wireless network. Key approaches include WPA, turning off unneeded wireless router services, using strong passwords, and reassigning SSIDs. I also recommend using XP SP2 which offers the most up-to-date support for wireless technology by Microsoft.
http://www.komando.com/tips_show.asp?showID=8796