Chances are this problem is caused by differences in your php.ini. register_globals is probably turned off in your new setup. If your php.ini's are the same, there are other mechanisms for changing the PHP configuration, e.g. .htaccess, httpd.conf, vhost.conf &c depending on what server and management software you're running.
Just phpinfo() and see what your local and master values are for register_globals. I presume $PHP_SELF is not printing anything and that's why your form isn't working, i.e. your output is <form ... action=""> If your action attribute isn't blank (and it prints the value of your current page), it might be a different problem. Also, if you have a 'funny' request URL like /form.php/contact-us/, Apache will drop the /contact-us/ bit as it would a query string.