As password security is the subject of the moment, due that MtGox thing, here's my system's function for it:
$salt = md5(rand().$name.microtime());
$passh = hash("ripemd160",$pass.$salt);
mysql_query("INSERT INTO users(user,pass,name,email) VALUES('$user','$passh','$name','$email')");
$myuid = mysql_insert_id();
mysql_query("INSERT INTO salt(uid,salt) VALUES($myuid,'$salt')");
$success = "You're now registered to this system";
?>
Your method is not good enough (not mentioning it seems you are not escaping properly variables when passing them to mysql).
I could do 50000 iterations of ripemd160 in 94.16ms without any optimization. I'd suggest you at least add some iterations to make bruteforcing harder.