I found incorrect $_SERVER[REQUEST_URI] on IIS7 using FastCGI.
In IIS7 using FastCGI, $_SERVER[REQUEST_URI] is not empty, and value same $_SERVER['SCRIPT_NAME']. When I use a plugin, It request http://wstour/wp-admin/plugins.php?page=xxx, example: http://wstour/wp-admin/plugins.php?page=qtranslate-config. But, $_SERVER['RequestURI'] return http://wstour/wp-admin/plugins.php
My computer:
Vista Home Premium SP1
IIS7.0 Fast CGI
PHP 5.2.6 Non Thread safe
Wordpress 2.5.1