Post order in category template

Hi there.
I am so close to achieving what I want to, but I can’t seem to get the syntax right.

What I would like to do is place posts with a certain tag at the top of the category listing.

I can’t figure out if this is something done inside or outside of the loop and whether it is a “query_posts” issue or a ‘<?php if” issue. Almost seems like I need to combine the two somehow…
“if has_tag=X show those posts first and then every other post in the same category”.
This would be universal across categories so I don’t believe I need to create a bunch of different category-X templates.

It’s late and I’m frustrated…I hope that question makes sense.
Thanks in advance.
~Xian