Centos – Installed PHP on CentOS, some features not working

I followed this guide to install PHP 5.3 on my CentOS 5 server:
http://www.webtatic.com/packages/php53/

I have phpMyAdmin extracted in a directory but it says it can't find the mysql extension. Moreover, I know I'll need the mysqli extension for other programs such as Drupal. The guide I followed says that those extensions come with it. When I run php -m it shows both mysql and mysqli though – that's where I'm puzzled.

I restarted apache and still no go. Where do you think my next step is?

phpinfo say my ini is in /etc/php.ini – should I be looking in there for something?

Thanks so much.