some months ago I had same question. unfortunately I did not get a setisfied answer. I tried Bamboo feed reader and other but noone did not me allow to work with RSS feeds in FF as I worked with them in IE.
And what is wrong with IE now? IE is simply becoming outdated and unstable.
So if anyone knows a good addon for rss or as FF terminology says "live bookmarks", I would very appretiate it.
I mean a good addon which can emulate an IE layout and can benefit of FF strenth.