I don't even remember when Kazaa came out, but I know as soon as k-lite came out I downloaded it and used it since I was tired of irradicating spyware from my system... but then month after month, more clients who were connecting to me were using the "k-lite master" network participation (ie: the number between 1-1000 that keeps track of how much you upload to download)
This is about the time the kazaa network went to crap for downloading most large files, especially when trying to get a whole TV series or something spanning many gigs. I think Kazaa's "network participation" was a GOOD thing - the ONLY thing I liked about the origional kazaa program, and when you totally ignore network participation, the leechers take over.
In the past couple months I've been using emule and have been able to download hundreds of gigs of files that actually work. Emule uses user "server side" recognition of "network participation" which is fairly ineffective when downloading small files like random mp3's (for which I still use k-lite) but emule works *much* better for large collections of files like TV show series.
What I always wonder is if k-lite had cleared out all the freeware but kept the queue system based on the network participation rating, would the kazaa network be as strong as it used to be? From my personal knowledge of dozens of serious sharers have all switched to other networks like edonkey, emule, overnet, bearshare etc. because they incorporated at least something of a sensible queue system.