Mac/Network connection problem

I connect my MBP OS 10.5.6 to the net wirelessly via 2Wire Gateway. This problem started when we switched from Uverse to ATT DSL. Every time I boot I have to run Network Diagnostics and reinput the WEP (no lectures on how much better WPA is, please). Keychain Access lists the Airport network p/w, but it doesn't appear to remember it for some reason. I've removed/reinstalled it in Keychain Access a dozen times. I've contacted ATT tech support, Apple forums and multiple searches w/ no success. It appears this is not an uncommon problem, but I've had this computer for two years and this is new to me. I would look favorably upon you if you could help me resolve this irritant.

Disregard. I've resolved it.

I am also having the same problem and cannot figure out. If you have already solved it, please kindly explain.

Unnop

WEP is worthless.