I would definitely NOT reccomend Kazza. Its adware invades your poota and the downloads can contain pernicious poota destroying code. This is not so much the problem wityh Kazza, but some of its brainless users. Unfortunately the stuff just keeps going round the Kazza community multipying as it goes. The whole thing is now riddled with destructive code.
I've used WinMX with few problems. But you have to be so carefull with any peer to peer system as there are no safety nets to catch deliberate destructive code. You have to use a lot of caution. Suspect everyone, trust no-one!