How to Update my Centos 5.7 server to the new 6.2 version?
Upgrading from 5.7 to 6.2 is a major upgrade, contrary to upgrading your system from 5.6 to 5.7, which is a minor upgrade.
yum can handle the minor upgrades.
Major upgrades apparently are not supported. http://centos.org/modules/newbb/viewtopic.php?topic_id=36050&forum=55
So if you want to upgrade your server from 5.7 to 6.2 , you are on your own.
The best way is too implement a new centos 6.2 server and transfer your files.