Lakota Wind Turbine

General "rules of thumb" for any wind genny are; the bottom of the swept area of the prop is at least 30 foot higher than anything within a 500 foot radius, and the daily wind speed (averaged over a year) is 10 mph.
Wind genny's will make power with less than this, but these "rules of thumb" take cost effectiveness into consideration.
Typically, wind genny's start to make power in the vacinity of 7 mph winds but dont make there rated power until about 28 mph winds. This varies of course from genny to genny.
Go to homepower.com and move your curser over -Education- then click on -wind- and then -maps and data- find your region on the map. The legend is small and hard to read but the scale is easy to understand. White is not good and the darker the blue the better it gets.
Even if you happen to live in one of the dark blue zones it might be a good idea to at least consider photovoltaics to "balance out" an off grid power system.
There is a lot to consider when making the move to off grid living but it is do-able. After all, mankind survived off grid for well over 7,000 years. Its only been about 100 years since the grid was concieved.