You can use any network capable computer as your start point. Once you reach out into the street or into the next street there are many ranges of equipment available to get the link made some of which are listed here . The typical range for a modest home installation is 1.5 km with direct line of sight. Some antennas enable longer distance connections point to point. You will need drivers for your networking interface which are distributed in the pack.
Much research is underway to enable trouble free set up an operation.
Several routing methodologies to get from point to point currently under consideration eg. Mobile Mesh, OSPF and MobileIP all have useful qualities but none as yet serves every requirement. If you need some help use the mailinglists. Certain project members are helping people get their nodes up and running and offering ongoing support and advise. With many folk in the same situation you will find the information flows.