I recommend aMule and Azureus as P2P programs for downloading non-copyright material on linux. They seem to be the most highly recommended by the linux community in general.
You can get the source for both of them free from
http://www.sourceforge.netAlso, if you like to protect your privacy, they both have options for restricting access from block lists. Although, I understand peerguardian is a better tool for blocking access. There's also regularly updated published lists of sites containing the IP addresses of music industry investigators and law enforcement agencies.
Peerguardian can be downloaded free from
http://phoenixlabs.org/pg2/
