One Care is not compatible with Windows 7. From the One Care end of sale guidance page:
I AM PLANNING ON UPGRADING TO WINDOWS 7, WHAT SHOULD I DO?
Windows Live OneCare will not be retrofitted for Windows 7 or on Windows XP Mode in Windows 7. Get more information on what
other security solutions you can use to remain protected. If you have uninstalled OneCare and would like to recover your OneCare backup files, you can do so by utilizing the
Windows Live OneCare Backup Restore Tool. If you want to run security software on Windows XP Mode in Windows 7, we recommend using
Microsoft Security Essentials.
http://social.microsoft.com/Forums/en-US/onecaregeneral/thread/81996436-edad-41ba-bdfc-02fc094e2ca9
Jim - MVP Windows Live - Forum Moderator - Live One Care - Live Mesh - Microsoft Security Essentials