you shouldn't really use the @ supresser until you are ready for use in a public environment, it's better to fix the errors than to hide them
try this instead a thinks it's what your after
[PHP]
$sql_email_check = mysql_query("SELECT * FROM users
WHERE email_address = '$email_address'");
$sql_username_check = mysql_query("SELECT * FROM users
WHERE username='$username'");
$email_address = mysql_num_rows($sql_email_check);
$username_check = mysql_num_rows($sql_username_check); [/PHP]
it should return the number of entrys that meet the supplied critera,
cheers
magic e