You know you could have just kept it in
one question...
What password are you entering? There tends to be either a plain text one (just some english word or something), or a hex one (sometihng like a3f634b5 etc.)
You may need to change the password to a more appropriate length, as here:
http://docs.info.apple.com/article.html?artnum =108058
This is due to the WEP design: this stuff wasn't specified! WPA is far better.
This document describes how to enter a plaintext password or a hex one of certain length:
http://docs.info.apple.com/article.html?artnum =106424