Kazaa and eDonkey are popular services, but their software arrives with unwanted adware and spyware. Shareaza has an appealing interface and it has no adware or spyware at all – and since it’s being developed as open source software, it’s likely to stay that way. More important, it reportedly connects to the eDonkey and Gnutella networks, making it more likely that you’ll get good results when you search. It also claims to support BitTorrent but it’s unclear how it searches for BitTorrent sources.
I haven’t tried it. Your mileage may vary. It may require configuring the firewall in your router and you may encounter bugs. As with any file sharing program, your IP address is exposed if you share any files – the RIAA wants your life savings and the Justice Department wants you to go to jail. Be careful out there!