Version 4.3.4 has support for pear. To enable pear you will have to modify PHP.INI
include_path = ".:/usr/share/pear"
Check your templates also in file
# /etc/e-smith/templates/etc/php.ini/50PathsDirectories
and restart your httpd service
Rgds, Ergin
PS : The latest version of PHP is v4.3.6 if you want to upgrade.