Low signal strength, hacking!! help!!!!

ok, i was asked to build a computer for a company. i did, when i brought it over they asked me to hook it up to their 2 person peer to peer network. it took a while to get it running, but its going. now, comcast (the area broadband company) comes in and installs the modem and line in etc and the connection between the two computers keeps breaking. the comcast line is using the nic i disabled. the wireless nics are d-link awd 520's i believe. also, someone hacked the computer and installed "serv-u" and they keep getting back door virus notifications. how can i fix this problem? if i encrypt the signals will the signal work as low as it is? oh, they are only ~20 ft apart and are radio, not line of site nics. this is a nitemare b/c they are 70 years old and work at a church.

....the crows seemed to be calling him, thought caw....

no firewall, but it isnt that connection thats the problem, its the connection between the two peer to peer computers using the wireless nics.

....the crows seemed to be calling him, thought caw....