zend server - php version upgrade

What is the best approach to upgrade from Zend Server CE 5.0 with php 5.2 to Zend Server CE 5.1 with php 5.3?

Uninstall and reinstall? Install over existing version?

With the existing setup itself you can upgrade Zend Server CE to higher versions. This can save your configuration time if you are having lot of configuration in your existing server

Check Page: 69 in the following pdf -

http://static.zend.com/topics/Zend-Server-CE-Installation-Guide-V40-n.pdf

You can upgrade Zend Server CE to Zend Server as well.