If you still have OneCare installed, you'll want to remove it -
How to Uninstall Windows Live OneCareThen, install OneCare from
http://onecare.live.com (the trial download) and after it is installed, click subscribe and log in with the LiveID used to purchase your subscription.
If you purchased a retail copy of OneCare, select the option to subscribe with a retail PIN/key after logging in.
if you encounter problems, you can contact support.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare & Live Mesh Forum Moderator