Go to Control Panel and select "Network Connections" and look for your wireless adapter. Right click it and select "View Available Wirless Networks". Your neighbor and your router should both show up in the next window. On the left you'll see "Change the order of preferred networks". Of course, if you're not seeing your router in the list then we have a whole new problem. You're absolutely sure that you don't have Wep set up on this, right?