what i was told by redhat using version 7.3 was to add the name you want in /etc/hosts and in /etc/sysconfig/network
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost Tron
my computer name is Tron.
edit: oh yeah, this change is not immediate until you reboot. you could run the hostname command (as root i imagine) setting setting this though to get the hostname in your current session.
something like i think:
hostname -F /etc/sysconfig/network
but i'm not sure. do a 'man hostname'