nixCraft posted a guide about upgrading from Centos Linux 5.4 to 5.5
>> HowTo: Update Centos Linux 5.4 to 5.5
CentOS Linux v5.5 has been released. How do I upgrade CentOS Linux from version 5.4 to latest version 5.5 over the Internet?
CentOS Linux v5.5 has been released and available via mirrors for immediate update. You can use the yum command to upgrade CentOS Linux as follows.
>> HowTo: Update Centos Linux 5.4 to 5.5
