OneCare is not designed to be updated manually, though it can be done.
If you have performed all of the troubleshooting short of a reinstall of OneCare, you also did not contact support.
I suggest doing so to resolve the issue.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
What, exactly, happens when you click "check for updates" in OneCare?
to manually download and install updates for OneCare -
http://support.microsoft.com/?id=958067Select the link for 32 bit, which is what you are running. The reference to 32 *or* 64 bit downloads applies to Vista and OneCare for Server, but not XP - OneCare only works on the 32 bit version of XP.
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator