Showing different posts on category pages

First make sure you’ve set your posts per page to 6 in the Reading settings – as I can see you’re displaying 2 columns of 3 posts. Then you need to add the page variable to the query_posts attributes, by adding this before you query posts:

$paged = (get_query_var('page')) ? get_query_var('page') : 1;

and then changing the query_posts function calls to:

query_posts('showposts=3&cat=1461&paged='.$paged);

and

query_posts('showposts=3&offset=3&cat=1461&paged='.$paged);

You’ll also want to cheange you links to the previous and next pages by using something like the next_posts and prev_posts tags or you can simply make it yourself by adding /page/2 (for example) to the end of the category permalink – if you’re using pretty URLs of course.

It would probably be a good idea to check that you’ve got more than 3 posts to display before running the query for the second column too.