preg errors

I'm using PHP version 5.1.6.

I'm getting this error:

warning: preg_match() [function.preg-match]: Compilation failed: support for \P, \p, and \X has not been compiled at offset 3 in /etc/drupal/www.kidsgardening.org/modules/pathauto/pathauto.inc on line 72.

I've attached a patch.