Information to help troubleshoot and resolve update problems -
http://social.microsoft.com/forums/en-US/onecareupdate/thread/9a6a0003-b91c-4518-966c-fc50450f0e41/
Note that the Windows Firewall *should* be off if you are using OneCare, which has its own firewall. If, however, you mean that the OneCare firewall is off and won't turn on -
Firewall repair tool - http://social.microsoft.com/forums/en-US/onecarefirewall/thread/e67b1989-afd5-47e5-a393-3a551c7c7e60/
If you are still having problems, please 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