That depends on what you want to do. Either dongle will work and the USB dongle costs less. If you want to use the Conductor in the futire then you would need the Etherdonge at that point. Since there are no coops for the USB dongle, you can order the board from the store and the parts from the BOM and get started right away. If you want the Eherdongle then you will have to wait for the next coop because currently, the Eherdongle board is only available during a coop for it. The one exception to the USB dongle right now is with the Academy coming up in less than 2 weeks, I doubt that RJ would be able to ship the board out to you until after the Academy is over.