Can you set them up in windows that can be seen from each others home? if so I use a Linksys BEFW11S4 wireless router/Access Point and a WUSB11v2.5 to connect to my sons home at this distance. We get 11mb connection with a 53/40 connection.
No extra or external antenna.I placed both in windows. turned on the USB configuration utility for the signal meter. then slowly moved them arround one at a time . When I got the strongest signal I mounted them in place.