Won't stay connected

Check in the XBOX settings to see if the TCP/IP settings are 1500 or 1514. (1514 is the default for TCP/IP)

Did you go through the encryption settings for WEP? There should be a setting on the router that allows gaming to pass through it.

Also, if the XBOX is encrypted in WEP, what length of key are you using. WEP is naturally unsecure (about 10 minutes on the internet because it is a static key), but that's all it can do.

Also, if there is a firewall setting through the router, check to see that it doesn't scan encrypted connections. (This can be even in the internet security).

Outside of this, there is not much else that can be the problem.

It's either the router settings or the Internet security package that you installed.