While you can always visit each site to verify and update your bookmarks, it's sometimes more convenient to subscribe to a "Live bookmarks" feed. The default Firefox bookmarks includes one such web feed, the "Latest Headlines".
If you are browsing a web site that has an available Live bookmark, RSS or Atom feed, this icon: will appear at the right side of the Location Bar (or at the bottom-right of the browser window if you are using Firefox 1.0.x.)
To add Live bookmarks, click the web feed icon:
If you have not previously set an automatic action to subscribe to feeds, set "Subscribe to this feed using" to "Live Bookmarks" and click "SubScribe Now".
The "Add Live Bookmark" dialog will appear. Modify the name and "Create in" location, if you wish. Click "Add".
Internet Explorer 7
Locate the RSS Icon on the right of the address bar at the top of your browser and click on it:
At the top of this page, you now have the option of subscribing to the RSS feed in either the RSS reader of your choice, or by using IE7 itself.
Click "Subscribe to this feed". A window will open and ask you where you'd like to save the live bookmark. Select a folder and click "Subscribe".