Not sure. You're breathing the same air I am... GIVE IT BACK!

I see it more as trespassing.

Actually....yes, it is. It's called stealing bandwidth. Monitoring is one thing...using is another. Kind of like monitoring radio transmissions...you can monitor ANYTHING you want, even frequencies used by the military and other government agencies. But you just can't TRANSMIT on any frequency you want.

Yes. Multiple PCs sharing the same connection mean that each PC will get less bandwidth, at least sometimes. Doing so without the person's knowledge and consent is like raiding their fridge.

If it's unsecured, then no and no you can't be prosecuted for it.

Thank's for your help chief but when I go to control panel click on wireless icon ,it ask me to setup a wireless network,the first option you gave isn't there.

Whoops, this wasn't supposed to be an answer, but a comment. So I'll edit it with an answer: Yes, it is stealing. You are not asking permission to use a service that someone else is purchasing.

It is stealing, but it isn't really illegal. I'm not saying that if you don't get caught, you didn't break the law. But, not only is there almost no way to tell if someone is sharing, identifying that person is almost impossible. I don't consider it illegal, because EVERY common brand of router has a way to secure your connection. If you are too lazy to set that connection, then you obviously don't care if people use your internet. If you leave 100 bucks in the middle of the street, then walk away, and someone picks it up, would you claim they stole it? NO. Now, it is technically illegal, and if you did get caught, then you wouldn't have a strong case in court. BUT! you can't tell the entire country that they can't eat canned green beans, and expect them all to follow that. People will do it no matter what. So, take the extra 45 seconds to set up a password. Even if it is just 1234. If someone still gets past, THEN it is very easy for you to prosecute, and you will have an almost flawless case. One other thing: If you are at your house, and have an unsecured network with the default name "linksys" then you go to another neighborhood, and someone else has the name "linksys". Your computer will automatically connect. The person who owns the network can see how many computers are accessing it. They can't tell where it is comeing from, or identify the person, but they can see that someone is there. If you don't use any resources, then they can't really do anything to you since it was an accident. This is another defense people can use in court. (its not a strong defense, but it is something)