I found this a great resource in moving from Classic ASP to PHP (or vice verse for that matter).  It is a three part article from language basics, functions, classes and ASP object equivalents. Very handy.

http://phplens.com/phpeverywhere/node/view/30

Request Querystring equivalent for PHP and ASP.

PHP
$_GET["MyVar"];

ASP
Request.Querystring("MyVar")