I've been along time user of the NewsFire RSS reader. Unfortunately, newer versions require OS X 10.4, and I have delayed upgrading my machines long enough that I'm just waiting for 10.5. Additionally, NewsFire is just incredibly slow (at least, the older version I can use) and crashes frequently. It might have something to do with the 360 or so feeds I track.
Anyway, I've left all my troubles behind, now that I've adopted the Vienna RSS reader. Fast and reliable. And free.