Custom Category CSS/Template

I’m trying to set a category up to display a custom header image and change the color of the hyperlinks on the given category. I’ve managed to get the sidebar working, but as far as the content and the header, no luck. I’ve read the codex and browsed the forum but can’t find a definite answer. Is there a way to tell wordpress if the post is in category-x then pull x-header and x-css-class/id, well ideally just the css as everything is in there (img url, etc) … though I could use a footer change?

Like I said, I’ve read over the codex and it looks like setting up category-x.php etc will change the layout, but not the header image or link color … am I right or wrong? And can what I’m asking be done?

Thanks for the help.