Show WP thumbnails differently depending on category

I've created a loop that's getting posts of a certain category and displaying them correctly.  I know have a new sub-category in that loop where the images have a different dimension and don't fit inside the existing CSS layouts.

Is there a way to distinguish and define the layout based on category?

I'm using (in_category('category-name')) currently which is working to define, but it displays twice since I can't remove it from the overall loop.

When I remove the category from the loop using query_posts('cat' => -150) it obviously removes completely.