Thank you for your fast reply.
I need to upgrade php from 5.1.6 to 5.2.6, it's a vbulletin requeriment.
Because "yum upgrade php" just say "No Packages marked for Update" I used 'remi repository' to upgrade php.
"yum --enablerepo=remi update php" and this is part of the log:
...Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Updating:
php i386 5.3.1-1.el5.remi remi 1.3 M
Installing for dependencies:
libedit i386 2.11-2.20080712cvs.el5 epel 79 k
libtool-ltdl i386 1.5.22-7.el5_4 updates 37 k
mysql-libs i386 5.1.41-1.el5.remi remi 2.1 M
sqlite2 i386 2.8.17-2.el5.remi remi 170 k
t1lib i386 5.1.1-7.el5 epel 194 k
Updating for dependencies:
php-cli i386 5.3.1-1.el5.remi remi 2.5 M
php-common i386 5.3.1-1.el5.remi remi 945 k
php-devel i386 5.3.1-1.el5.remi remi 615 k
php-gd i386 5.3.1-1.el5.remi remi 202 k
php-imap i386 5.3.1-1.el5.remi remi 79 k
php-ldap i386 5.3.1-1.el5.remi remi 50 k
php-mbstring i386 5.3.1-1.el5.remi remi 2.1 M
php-mcrypt i386 5.3.1-1.el5.remi remi 36 k
php-mysql i386 5.3.1-1.el5.remi remi 140 k
php-pdo i386 5.3.1-1.el5.remi remi 162 k
php-xml i386 5.3.1-1.el5.remi remi 203 k
Transaction Summary
================================================================================
Install 5 Package(s)
Update 12 Package(s)
Remove 0 Package(s)
Total size: 11 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Check Error:
file /etc/my.cnf from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/charsets/Index.xml from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/charsets/cp1250.xml from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/czech/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/danish/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/dutch/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/english/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/estonian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/french/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/german/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/greek/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/hungarian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/italian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/japanese/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/korean/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/norwegian-ny/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/norwegian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/polish/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/portuguese/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/romanian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/russian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/serbian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/slovak/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/spanish/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/swedish/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/share/mysql/ukrainian/errmsg.sys from install of mysql-libs-5.1.41-1.el5.remi.i386 conflicts with file from package mysql-5.0.77-3.el5.i386
file /usr/lib/php/modules/fileinfo.so from install of php-common-5.3.1-1.el5.remi.i386 conflicts with file from package php-pecl-fileinfo-1.0.4-1.el5.rf.i386
Error Summary
-------------
If "yum --enablerepo remi upgrade mysql" then
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Updating:
mysql i386 5.1.41-1.el5.remi remi 3.9 M
Installing for dependencies:
libedit i386 2.11-2.20080712cvs.el5 epel 79 k
libtool-ltdl i386 1.5.22-7.el5_4 updates 37 k
mysql-libs i386 5.1.41-1.el5.remi remi 2.1 M
mysqlclient15 i386 5.0.67-1.el5.remi remi 1.3 M
sqlite2 i386 2.8.17-2.el5.remi remi 170 k
t1lib i386 5.1.1-7.el5 epel 194 k
Updating for dependencies:
mysql-server i386 5.1.41-1.el5.remi remi 11 M
php i386 5.3.1-1.el5.remi remi 1.3 M
php-cli i386 5.3.1-1.el5.remi remi 2.5 M
php-common i386 5.3.1-1.el5.remi remi 945 k
php-devel i386 5.3.1-1.el5.remi remi 615 k
php-gd i386 5.3.1-1.el5.remi remi 202 k
php-imap i386 5.3.1-1.el5.remi remi 79 k
php-ldap i386 5.3.1-1.el5.remi remi 50 k
php-mbstring i386 5.3.1-1.el5.remi remi 2.1 M
php-mcrypt i386 5.3.1-1.el5.remi remi 36 k
php-mysql i386 5.3.1-1.el5.remi remi 140 k
php-pdo i386 5.3.1-1.el5.remi remi 162 k
php-xml i386 5.3.1-1.el5.remi remi 203 k
Transaction Summary
================================================================================
Install 6 Package(s)
Update 14 Package(s)
Remove 0 Package(s)
Total size: 27 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Check Error:
file /usr/lib/php/modules/fileinfo.so from install of php-common-5.3.1-1.el5.remi.i386 conflicts with file from package php-pecl-fileinfo-1.0.4-1.el5.rf.i386
Error Summary
-------------
And now I don't know what to do because I'm afraid about make a mess. I'm noob in Linux.
This is why I ask for advice, I could be doing the upgrade in wrong way.