Live Primus is a great thing. Saw them in 2006 at the Tabernacle in Atlanta, saw Les Claypool with C2B3 and once with his Fancy Band, always had a blast. Do you remember what year you saw them or what album you owned? You should check out my Primus thread, I've posted lots of goodies in there!
http://forums.ledzeppelin.com/index.php?/topic/21019-primus/