What happens when you try to purchase a subscription?
To subscribe to OneCare, you need to click the link in OneCare and log in with a LiveID. You then need to provide payment information in the form of a valid credit card.
If you have problems with the purchase process, 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, & MS Security Essentials Forums Moderator