|I know you said that you can connect to other networks but disable the firewall just in case something is being over looked. Also try a static IP, out of the DHCP range, on your subnet.|
As a side note, WEP is not the most secure encryption. I've been testing WEP and securing networks for people. In every case so far, I have found that nobody changes the default password in the router. No one seems to use static IPs either and the router is giving out connections once WEP is compromised.