Do not waste your money on expensive Wifi Analyzer hardware and software just pickup a Droid phone and download the Wifi Analyzer utility for free. This tool is useful in identifying networks that overlap and will allow you to determine if you’ve made the right decisions about the channel your wireless device is using. You can quickly and easily see if there is a strong wifi signal that overlaps yours. Unlike my example you should perform this analysis where you intend to USE your wifi client devices most. Here is a video demonstration for more clarity: