Ya that's what I was getting at, high gain and directional. I am asusming You already have a wireless router at your house and I am assuming and you need to access the other house. You can just try and add a USB high gain antenna to your friends house and let him connect to your wireless gateway. Several people have posted great links. I have found this one useful when pointed directly at a gateway.

The stand alone USB adapter is here:
http://www.hawkingtech.com/prodSpec.php?ProdID=158

And the antenna only is here:
http://www.hawkingtech.com/prodSpec.php?ProdID=143

These are all indoor antennas