[CentOS] RHEL5 and CentOS 5 root logins

I found, under a 64-bit CentOS 5 workstation install, it is possible to 
modify /etc/inittab and add a couple of lines to prevent root from logging 
into the console.

I found, under a 64-bit RHEL 5 server install, adding the same two lines 
completely breaks the OS, to the point that a reboot after the lines are 
added, the OS brings you to a fsck-like prompt, and other things break, 
too.  I didn't have time to look at the logs for specifics, if any were 
recorded.

Does anyone know if a CentOS 5 server install option permits locking out 
root from console login?   Does anyone know of a way, in RHEL 5 Server 
edition, to prevent root from a console login?

Thanks.

Scott