How to know if someone is hacking your wireless

Useful info
How to find out who's using your wireless - Wireless - Internet & Networking

Would suggest that you set up a wireless PW for your router, this way no one without it would not be able to use your service

That link above is very useful.I would try to simply secure what you have first before anything else. Also hiding your SSID will be semi-useful but is in no way an only option. Since hing you SSID only stops those who don't know your SSID. Anyone who's previously connected to it will still have acces ( I believe this is how it works) I was always a fan of MAC filtering but it got to be to tedious when you have 1,000 friends and they all want access :D

I would say use some sort of security. What kind of router is it and we can walk you through it. (make and model)

Rick