seeing other networks

I am hooked up to a linksys-g router and I have a B
network centrino with XP pro. I use MAC filtering and am
locked down with a successful WPA utilization. No
problems there. Whenever my neighbor logs on to his
unsecure network, my machine sees his "default" network,
which I can surf if I choose, I then have a problem
getting the internet served to me by my router. I want to
lock out his network from my computer so I can't see his
network. Can I do this? I know he is locked out of mine,
but since his is unsecure, I can see his and my computer
tries to configure his into my machine.

Privsman