in a word no. The frequencies are different.
When you configure a wireless network you should always select to encrypt it. You can put in a code and only computers with that code entered will be able to get into your network.
I could see a network in a house across the street and access it. I popped over and encrypted it. I can see the network listed, but cannot access it now. (I got the people to enter a code and not tell me what it is).