The following Office 2007 updates failed to install on Windows Vista Business with Error Code 57A:

KB950130, KB951338, KB951944, KB951596, KB954326, KB956080, KB951546

Examing the %systemroot%\Temp\MSI*.log files revealed that the admin account did not have access to the registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Uninstall\ENTERPRISER

Giving the administrators group and the system account ownership and Full Control of the registry key resolve the update issues.