PHP error on F7

[Eric]

Good morning, all...

I'm getting ready to install some PHP applications on F7 (specifically, 
horde and turba).  To check my PHP version I said:

php --version

and got:

PHP Warning:  PHP Startup: apc: Unable to initialize module
Module compiled with module API=20050922, debug=0, thread-safety=0
PHP    compiled with module API=20060613, debug=0, thread-safety=0
These options need to match
  in Unknown on line 0
PHP 5.2.2 (cli) (built: May  8 2007 08:15:05)
Copyright (c) 1997-2007 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2007 Zend Technologies

First of all, what is "apc"?  Do I need it?

If I go to /etc/php.d/apc.ini and comment out "extension = apc.so" and set 
apc.enabled to 0, the error message goes away and in response to "php 
--version" I just get:

PHP 5.2.2 (cli) (built: May  8 2007 08:15:05)
Copyright (c) 1997-2007 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2007 Zend Technologies

I'm happy with just doing that unless apc is something I need for some reason.

My guess is that during the system update, php was updated but apc wasn't, 
hence the "options need to match" message.