I was also going to mention otherpower.com. It is a fantastic site with a lot of very knowledgable members. While a horizontal-axis wind turbine will usually outperform a vertical-axis wind turbine there are some situations where a HAWT is not a good choice. If you live in the city is the one that comes to my mind. A rule of thumb for how high to build a HAWT is 30' above the tallest obstruction in a 300' radius. A VAWT can deal with the more turbulant air closer to the ground. Check out www.windstuffnow.com Ed Lenz has built an incredible VAWT that pumps out a pretty decent amount of power.