md5() with salt encryption - PHP

i was wondering if anybody can tell me how to Encrypt a specific HASH with a Specific Salt
i mean its like to be double hashed with a specific Salt

i tried sumthing like

<?
$hash = md5($md5_1 . $salt) ;
echo $hash ;
?>

as an example i used :
md5.php?md5_1=22ad09cd99118be452e1603d0574cef1&salt=wGK

but the result was always the same
d41d8cd98f00b204e9800998ecf8427e
even if i didn't pass a value for md5_1 and salt

well am a Beginner or less :D but need help to make that.

Well for one that won't work if register_globals is turned off, which it is by default, so it was hashing two null values.

PHP Code:

---

<?PHP
$hash = MD5($_GET['md5_1'] . $_GET['salt']);
echo $hash;
?> 


---

Though that is simplistic and probably only useful as an example.

thx chsh

You're welcome.