PHP Content Management System

I'm looking for a good PHP content management system. I need one that will allow me to write custom php modules for it, so that I can create an Enterprise web applications.

I don't know if anybody has uses DotNetNuke, but its a CMS that is based on asp.net. If I can find something like that for PHP, that would be awesome. I've never used PHP Nuke before and didn't want to pay for it before I was sure it was what I wanted to use.

Also, I use Microsoft SQL and not MySQL, which I have not found a CMS that suppose MSSQL, so I might have to switch to MySQL.

Thanks!
Jordon

I don't know why you would pay for PHPNuke. It's open source. Here check out these Open source CMS/Portals There's a variety to choose from and you can view working demo's of each to evaluate them before you try them. They are all free, including PHPNuke.

http://php.opensourcecms.com/scripts/sh ... %20Portals

Several of my friends are really into Joomla.