Sorry if this is a stupid question....

I am getting an exception that says, "The mysql driver is not currently installed". I ran "pecl install pdo" and that worked fine. I never had a php.ini file, so I created one that contains the line "extension=pdo.so" and saved it in my /usr/local/apache2/conf directory. Then I added the line PHPIniDir "/usr/local/apache2/conf" to httpd.conf. Basically, I did what seemed like easiest way to add a php.ini file from all of the examples given in the php documentation. I am running Linux, so none of the Windows methods will work for me. Then I restarted httpd. But I still get the message that the mysql driver is not installed. Have I done something wrong, or forgotten something? Is there an easier way to tell php where to find the php.ini file?