We are currently running a Linux server running WHM/cPanel that has about 40 accounts on it. It currently has PHP 5.2 and our new webapp requires a minimum of 5.3. We would like to upgrade to 5.3 without disturbing any of the existing websites. This would require properly scoping out the project beforehand by documenting the requirements and current PHP configuration so that any new PHP installation would not break existing sites. We attempted to do this with our hosting provider the other day and it resulted in more than 30 hours of server down time and a full restoration of 5.2. We'd like to try again with someone that knows what they are doing. We would also be interested in general maintenance and security-related suggestions. It would be helpful if you knew something about ini.php files and general PHP configuration... some of our older sites rely upon Zend Guard so this would have to be maintained.