Daniel...I would suggest you not spend your money on this model OR any small blade wind generator. Read the Practical sailor reviews from summer 2007.
Only the large blade units give you meaningful output inn 10 knots of less.
This graph is from 4 winds so throw their unit as biased...but look at the Rutland in relation to others.
On the good side...it is quiet!
EDIT...here is a Practical Sailor test of several including the Rutland:
wind.JPG
http://www.mactrashop.co.uk/superwind-report.pdf for full details.