Networking Trouble

Hello, i am new to this board. In my home, we have a desktop running windows XP, connected to a wireless router(We use a Linksys router) My personal computer is a Laptop running Windows vista Basic. Recently, My laptop has become unable to connect to the internet. I tried to reconnect by manually restarting the Router, which usually works, but this time, i received no success. I tried connecting to our network using my PSP, to test if the problem was with my Laptop, but i ran into the same problem, getting and error massage saying that the access point could not be detected.

When at my "Connect to" window on my laptop, i become connected to several Random networks, including "Linksys through "Linksys(4)" with very low signal strength. My main network "Stargate" will show up on my list randomly, first saying that I'm not connected, and giving me an error message saying that i cannot connect successfully, but When i diagnose the problem, Windows can't find any problem with the connection. Afterwards, if i go back to the "Connect to" window i'll somehow be connected back to my regular network, "Stargate ". Even though it appears as if i was connected, i still can't get access to web pages. but whenever i'm connected to a "Linksys" Network, I can get access to web pages, but they load extremely slowly. The Networks on my list disappear and reappear at random. help with my dilema would be greatly appreciated.