I’m looking for a free RSS Windows reader that will:
1. Allow me to check multiple feeds for any updates every XX minutes.
2. Runs in my Windows taskbar and will do a pop-up notification when a feed has been updated.
http://www.yeahreader.com - is also good rss feeds reader
if you are using Google reader, you can try the Google Reader Notifier for Windows that stays in the taskbar and alerts you.
FeedDemon! Definitely my favorite. It syncs with Google Reader as well so if you want to make the switch (like I did) it's an easy transition. lol
What about a FF add-on that notifies within FF? Try infoRSS.