Código PHP:
$result = mysql_query("SELECT * FROM usuarios WHERE nick='".
$HTTP_COOKIE_VARS["usNick"]."' AND password='".$HTTP_COOKIE_VARS["usPass"]."'");
$row = mysql_fetch_array($result);
if(mysql_num_rows($row) == 1){
$userConected = true;
} else {
$userConected = false;
}
mysql_free_result($result);
Así