On the computer where One Care is isntalled, open One Care>Help>About Windows Live One Care and you will see the Live ID associated with your subscription. You can then contact support for help with recovering the password. How to reach support - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90Jim
You can use the free Microsoft Security essentials for malware protection - http://www.microsoft.com/security_essentials/resources.aspx
See this post for End of Life information for Windows Live OneCare - http://social.microsoft.com/Forums/en-US/onecaregeneral/thread/81996436-edad-41ba-bdfc-02fc094e2ca9-steve