What you can do is buy a wireless extender or get a Access Point. Put the Access Point upstairs. You will need some CAT 5 cable to connect the Router to the Access Point. This will improve your connection on the 2nd floor.
It works OK without WEP. But if I put WEP / WPA on, it'll connect to the network, but not to the interwebs. Whies?
Update now, wont work if I change anything. If I disable to the firewall on router, change the wireless name, put encryption on, it won't connect to the internet? This is bad [it wont connect on main computer plugged into it either!]
It looks like you have a messed up wireless router. I would buy a brand new Linksys G Wireless router.
