i keep picking up someone elses wireless signal. how do i stop it?

[Lifer]

i'm at a corner of the house where my own signal is less than stellar and occasionally i'll pick up someone elses signal and drop my own.
i wouldn't mind but his signal is even weaker than mine which is funny that it would use a weaker one instead.
how can i stop this?

winXP, orinoco gold, smc 802.11b router

 

[ZeroNine8]

secure your access point with WEP or WPA and set your computer so you don't automatically connect to unsecured networks. You can do this in network properties as well as set your network preferences and add/disable networks in your wireless network properties.