I'm not clear on your situation. Is this a new subscription that you were activating? You signed in with the first email address, but your password was not recognized? If so, you can't have proceeded with activation.
I'm thinking that you mean that you are reinstalling or installing to a second PC. If your subscription was created with the first email address, which is your LiveID, you will need to use that to activate a reinstall, activate an install to another PC, or manage your account. If you don't know the password, you can get it reset at http://account.live.com or contact support for help -
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve