Randy Sandberg on "missing the MySQL extension"

You can run WordPress without having a php.ini file. What I've seen most is that folks create one in order to change the MAX upload file size.

Here's a handy guide for the php.ini file:

http://us.php.net/ini.core

Also, you can quickly find out all about your current PHP state by:
1. Creating a file called phpinfo.php
--> actually, as long as it ends with .php you can pretty much name it anything you wish
2. Pasting this into it:

<?php

 phpinfo()

?>

3. Placing it in your site's root directory
--> at least that's where I always put it
4. Then simply point your web browser to http://www.mysite.com/phpinfo.php

And BOOM! All kinds of helpful PHP info will be displayed. Then, after you tweak things with your new php.ini knowledge, you can see the fruits of your labor by rerunning this phpinfo.php file.

Oh, this is only for testing purposes. NEVER leave the phpinfo.php file where anyone else can gain access to it being that some of the info shared might help compromise your system.

Hope this helps!