Thanks for all your replies. The point (above) that the weight isn't really a factor definitely helps clarify things.
Yes, I'm doing a Savonius design. I don't want to decapitate anybody on the lawn with long blades, and I want something compact I can move easily. So I'm thinking two thin plywood disks three feet across for the top and bottom. For the scoops I'm thinking cylindrical steel conduit used for heating ducts (six or eight inches in diameter), cut down its length, maybe three or four feet high. A 1/2 inch threaded steel rod would run down the center and drive the load. There's the issue of how many scoops: four seems too few, eight to many, so I thought six. I think this is a factor in evening out the torque. I keep trying to imagine what an ideal turbine would be like: would it have many closely spaced scoops? But if the wind is from a given direction, don't they then just block the wind from their neighbor?
I've heard that you can use two toroidal Neodymium magnets as a bearing for this kind of turbine: the steel rod would go through them, the magnets would repel each other, and the turbine would be levitated.