I live in a small apartment complex, I am a current client of a cable company and I have high speed internet. I live on the upper floor, then there is a pool in the center of the complex and my brother lives in the bottom floor. Both of us are mac users, I have an powermac G4 Dual 1.42 and he has an iMac G4, 1 Gz. I want to get my brother to share the same internet connection using airport express. I called my cable company asking if I could share internet connection and they told me that it was illegal. But then I rephrased the question and I asked them if I could share a wireless signal to my brother from my computer and get his computer to enter to the internet. The costumer service rep said: How would we find out? I don't see why not. So I am puzzled.
Guys, is this legal or not? Can my brother share my internet signal through airport?
Now that we got excited about it, 2 more computer users in our apartment complex want to join me and use my signal to connect also, split the costs on the bill (pretty cheap for everyone) so it will be a total of 4 connected to my signal. Is this legal?
Now the second problem. As I mentioned, my brother is a mac user just like me. My friends are PC users. What do they need to connect to my signal? Is there such thing as an airport card for PC?

Guys, is this legal or not? Can my brother share my internet signal through airport?
Now that we got excited about it, 2 more computer users in our apartment complex want to join me and use my signal to connect also, split the costs on the bill (pretty cheap for everyone) so it will be a total of 4 connected to my signal. Is this legal?
Now the second problem. As I mentioned, my brother is a mac user just like me. My friends are PC users. What do they need to connect to my signal? Is there such thing as an airport card for PC?