Update standard settings

Can any one help with this?

The problem i am having is, i can not find out what the standard
settings for windows update on the following :-

Microsoft Windows Server 2003, Standard Edition
• Microsoft Windows Server 2003, Enterprise Edition
• Microsoft Windows Server 2003, Datacenter Edition
• Microsoft Windows Server 2003, 64-Bit Enterprise Edition
• Microsoft Windows Server 2003, 64-Bit Datacenter Edition
• Microsoft Windows XP Home Edition
• Microsoft Windows XP Professional
• Microsoft Windows XP Media Center Edition
• Microsoft Windows XP Tablet PC Edition
• Microsoft Windows XP 64-Bit Edition
• Microsoft Windows 2000 Advanced Server
• Microsoft Windows 2000 Professional
• Microsoft Windows 2000 Server

I know how to change registry setting to stop and start the automatic
update service, how ever i keep on finding information on the web that
Contradicts each other, some sites say they will automaticly update
after a certain time period ie 72 hours, and some say thay you have to
enable it first, so does any one know which if automatic update is
enabled by default or do you have to switch it on.

Thanks in advance

Bill