How can I make sure that search engine spiders don't index certain categories in my store? Specifically, I really don't want anything in my Santa category showing up on search engine hits. I sell ornaments (for example), and they're in two categories. The Santa category is only for a specific group of people, and if you hit my ornaments category under the Santa category, you may be confused if you didn't visit with Atlanta's Santa. Would my robots.txt just have this?

User-agent: *
Disallow: /store/index.php?main_page=index&cPath=75
Thanks for any help.