My aunt/uncle have a place on the shore of Saginaw Bay (basically Lake Huron) with an older windmill (it came with the house 20 years ago, and wasn't new then). That mill can power the entire house and send enough electricity back up the line to net them $50 or so each month.
It's been several years since I've been there, but when it was running it really wasn't very loud at all. I would imagine that newer units would be even quieter and most likely more efficient as well.
The windmill may never pay for itself, but few "green" alternative energy sources are really economically viable anyway. When you have power during a storm, the "pay off" period will suddenly shorten dramatically
