Following this guide below doesn't seem to work for me.

http://wiki.centos.org/HowTos/PHP_5.1_To_5.2

When I type yum update on root it says
"# yum update
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
* rpmforge: ftp-stud.fht-esslingen.de
Reducing CentOS-5 Testing to included packages only
Finished
277 packages excluded due to repository priority protections
Setting up Update Process
No Packages marked for Update"

Hi,

Since you're using CentOS, follow this webtatic repo how-to,
go to almost bottom of page under section PHP 5.2.17

I did it and it works without any problems.


good luck

# rpm -Uvh http://repo.webtatic.com/yum/centos/5/latest.rpm
Retrieving http://repo.webtatic.com/yum/centos/5/latest.rpm
warning: /var/tmp/rpm-xfer.ncGWpR: Header V3 DSA signature: NOKEY, key ID cf4c4ff9
Preparing... ########################################### [100%]
package webtatic-release-5-2.noarch is already installed
# yum --enablerepo=webtatic install php
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
* rpmforge: ftp-stud.fht-esslingen.de
Reducing CentOS-5 Testing to included packages only
Finished
410 packages excluded due to repository priority protections
Setting up Install Process
Package php-5.1.6-27.el5_5.3.x86_64 already installed and latest version
Nothing to do
# yum --enablerepo=webtatic update php
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
* rpmforge: apt.sw.be
Reducing CentOS-5 Testing to included packages only
Finished
410 packages excluded due to repository priority protections
Setting up Update Process
No Packages marked for Update

well, from this I can only see that you have YUM messed up Repo's

try this:
It's written there to exclude PHP v5.3 so you should do that.

If still no PHP is found, then try deleting YUM repo info
and take a look at this post where yum has troubles,
or maybe yum how-to if you want more to know about yum.

It seems to me that "webtatic" repo is not searched for packages so you get
"No Packages marked for Update"
because only "rpmforge: apt.sw.be" repo is searched.

good luck