In category and get_posts(offset=X)

Using get_posts i want to show different offset depending on wich category the post is.

+++ How do i change this code

<?php
$posts = get_posts(‘numberposts=5’);
foreach($posts as $post) :
setup_postdata($post);?>
<?php endforeach; ?>

+++ To something like that?:

<?php if ( in_category(5) ) {?>
get_posts(offset=1);

<?php if ( in_category(7) ) {?>
get_posts(offset=2);