unless he has some electronic surveillance equipment, no. but should he realise your leaching off his internet, he'll probably encrypt his network.... if he can figure out how.
All he has to do is look up his network clients list to notice you, but running an unencrypted wireless network is pretty noobish so that's probably not going to happen any time soon. When you suddenly don't have internet access, you'll know he's figured it out.
There's a little thing in your start menu, named Network.
Clicking on it will show you all the networks you are connected to and all the devices connected to it.
Including your computer and his computer.
There are dozens of ways to see who's on the same network as you, none of them hard or in any way 'techy'.
If he wants, he can see you on it.
He probably won't look though, seeing as he's too silly to put a password on his network.
![[Image: greed.png]](http://img585.imageshack.us/img585/4536/greed.png)
![[Image: qz7DdPp.png]](https://i.imgur.com/qz7DdPp.png)