To create a different feed for each category of your blog, you can use WP built in codex to specify different feeds for different categories. For instructions, see http://codex.wordpress.org/WordPress_Feeds and scroll down to the text just before the heading Adding Feeds.
Following are couple plugins that automate this process:
- Feedburner Category Feeds Plugin: http://www.2very.com/wordpress/plugins/feedburner-category-feeds-plugin/
- Category Specific RSS Feed Menu: http://wordpress.org/extend/plugins/category-specific-rss-feed-menu/
And here’s an older article from Perishable Press that may be helpful. I need to read it and try it out before I can specifically recommend it for WordPress 2.7. http://perishablepress.com/press/2006/11/20/add-rss-feed-link-icons/
Let me know if you’ve tried any of these and how they’ve worked for you.