Q: dear Apple: where/what is my Mac OS X login keychain pl,

Keychain is the repository for stored passwords. Normally your keychain has the same password as your login. However, if you changed your login password, the keychain didn't get changed.

If you know your old password, you can change your keychain password in Keychain Access. If you don't know it, you'll need to reset your keychain. http://support.apple.com/kb/ts1544