Excuse if I'm missing something here, but if you don't want a post to show up in your category page, then simply go back and edit the post, and take that category off that post. You choose to categorize that post with that category - now just uncheck the box and uncategorize that post with that category.
Again, my apologies if I'm missing something.
Hava
PS When I try to go to your site, it gives me an error message. I just thought you might want to know.