HPool,
Create a page where you normally do and call it "phpinfo.php". Just put the following code:
<?= phpinfo() ?>
Bring up this page in your browser and look about 5 items down for "Configuration File (php.ini) Path". That will tell you where your active php.ini file is.
As far as register globals not turning on, make sure you are restarting apache properly. Let us know if you're running Linux or Windows. The main thing is, make sure you completely "stop" apache and then "Start". Do not just use apachectl restart. It usually needs a full signal kill.
I can give more specific instructions if you tell us the OS this is on.
As an aside, register globals not being on is not a bad thing. If your're just starting this site out and have no older code to retrofit I recommend not using it. Just collect vars in the $GET, $POST, $_SESSION etc. arrays.
Good luck!