use the get_query_var and is_category functions.
<?get_header()?>
<?
if (is_category()) {
$page = (get_query_var('paged')) ? get_query_var('paged') : 1;
if ($page == 1) {
echo category_description(); //you don't need to include the category id on the actual category page - wordpress figures it out.
}
}
?>
