// Fix for IIS, which doesn't set REQUEST_URI
if ( empty( $_SERVER['REQUEST_URI'] ) ) {

// IIS Mod-Rewrite
if (isset($_SERVER[‘HTTP_X_ORIGINAL_URL’])) {
$_SERVER[‘REQUEST_URI’] = $_SERVER[‘HTTP_X_ORIGINAL_URL’];
}
// IIS Isapi_Rewrite
else if (isset($_SERVER[‘HTTP_X_REWRITE_URL’])) {
$_SERVER[‘REQUEST_URI’] = $_SERVER[‘HTTP_X_REWRITE_URL’];
}
else
{
// Use ORIG_PATH_INFO if there is no PATH_INFO
if ( !isset($_SERVER[‘PATH_INFO’]) && isset($_SERVER[‘ORIG_PATH_INFO’]) )
$_SERVER[‘PATH_INFO’] = $_SERVER[‘ORIG_PATH_INFO’];

// Some IIS + PHP configurations puts the script-name in the path-info (No need to append it twice)
if ( isset($_SERVER[‘PATH_INFO’]) ) {
if ( $_SERVER[‘PATH_INFO’] == $_SERVER[‘SCRIPT_NAME’] )
$_SERVER[‘REQUEST_URI’] = $_SERVER[‘PATH_INFO’];
else
$_SERVER[‘REQUEST_URI’] = $_SERVER[‘SCRIPT_NAME’] . $_SERVER[‘PATH_INFO’];
}

// Append the query string if it exists and isn’t null
if (isset($_SERVER[‘QUERY_STRING’]) && !empty($_SERVER[‘QUERY_STRING’])) {
$_SERVER[‘REQUEST_URI’] .= ‘?’ . $_SERVER[‘QUERY_STRING’];
}
}
}

或者这里 看里面的程序是这样写的
可以参考这里来设置
* Instructions: http://neosmart.net/blog/2006/100-apache-compliant-request_uri-for-iis-and-windows/
* Support: http://neosmart.net/forums/forumdisplay.php?f=17
* Product URI: http://neosmart.net/dl.php?id=7