Step 1: First of all we need to import some RPM Keys:

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY*

Step 2: Now we will remove all software groups, to get Centos to a minimum
Step 2.1: Run grouplist to see what software groups that are installed:

yum -C grouplist

Step 2.2: Remove all groups that are installed EXCEPT "Yum Utilities"

yum -C groupremove "GroupName"

Step 3: Lets disable unneeded services:

chkconfig --level 123456 haldaemon off
chkconfig --level 123456 lvm2-monitor off
chkconfig --level 123456 messagebus off
chkconfig --level 123456 netfs off
chkconfig --level 123456 atd off
chkconfig --level 123456 psacct off
chkconfig --level 123456 rdisc off
chkconfig --level 123456 ip6tables off
chkconfig --level 123456 smartd off
chkconfig --level 123456 pcscd off
chkconfig --level 123456 readahead off
chkconfig --level 123456 readahead_early off
chkconfig --level 123456 rawdevices off
chkconfig --level 123456 anacron off

Step 3.1: Use this command to check what services that are setup to run

chkconfig --list | grep :on

Step 3.2: You should have these services running:

anacron, crond, iptables, irqbalance, kudzu, mcstrans, network, readahead_early, restorecond, sshd, syslog, sysstat, yum-updatesd

Step 4: Lets upgrade Centos to the newest, and install some tools:

yum -y upgrade
yum -y install wget bzip2 unzip zip fileutils gcc gcc-c++ ncurses-devel pam-devel libxml2-devel libxslt-devel m4 flex byacc wget which
yum -y install pcre pcre-devel binutils autoconf automake libtool zlib lsof man man-pages mlocate quota rsync sysstat vixie-cron bzip2-devel

Step 5: Add RPMForge Repos for usage later.

(32Bit) rpm -Uhv http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
(64Bit) rpm -Uhv http://apt.sw.be/redhat/el5/en/x86_64/rpmforge/RPMS//rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm

Step 6: Remove and disable IPv6:

nano -w /etc/modprobe.d/disableipv6.conf
Add line: alias net-pf-10 off
Add line: alias ipv6 off
Save

nano -w /etc/sysconfig/network
Change NETWORKING_IPV6=yes to NETWORKING_IPV6=no

Step 6: Install and syncing NTP time service:

yum -y install ntp
chkconfig --levels 235 ntpd on
ntpdate 0.pool.ntp.org
/etc/init.d/ntpd start

Step 7.1: Changing server hostname:

nano -w /etc/sysconfig/network

Step 7.2: Find HOSTNAME= and change it to etc srv01.maxisecure.com or something else of your choice:

HOSTNAME=srv01.maxisecure.com

Step 7.3: Run this command to make sure that newly created files dont get readable by everybody

umask 077

Step 7.4: Now a reboot:

shutdown -r now