I've got a Linsys Wireless

Question

I've got a Linsys Wireless G 2.4, 54 Mbps, model WRT54G. I live a a house where other houses a a fair distance away. The strongest signal from a lynksys now shows it as secure whreas before it was unsecure and that is how we originally set it up a couple years ago. We bought a new laptop and intiially it work fine on the wireless. Now all the sudden we can't connect or when we do it connects on another signal that is unsecure but very very weak. I can't access the strong signal because I don't have the password. I started reinstalling the linksys router software but it doesn't seem to have anything about connecting with Vista which my new desktop has. Frustrating. Can somebody give me a suggestion on how to proceed. It seems like the new laptop would connect if I just had a strong signal.