Well yes it is true. With wireless you are always open to people being able to drive up your street and see that you have a wireless connection running and be able to exploit/log onto it.
This can be prevented however if you set it up correctly, as far as I know. I don't know anything about wireless security as far as doing it, but I do know the reprocussions that can be had from improper setup. Just be careful and try to read as much as you can about securing the connection.