Do you have the retail product key? If so, you can provide that to support. You will have to use email support, though, as you don't know your LiveID for the account. Circuit City should have provided a paper with that LiveID when they set up your account.
How to reach support - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
Select the option that you are a "trial or beta" user so that you can proceed without account validation.
-steve