A reminder to self (this should work for all BSD-like systems, including Fedora & RHEL) —
Edit /etc/inittab as root. The number after the first colon after id is the default runlevel.
id:3:initdefault:
BTW, I prefer runlevel 3 (no GUI).
Reference: http://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-boot-init-shutdown-sysv.html