I use a Mackie 808s powered mixer and two C300 passive 2-way speakers. It's a great flexible system; I've played for 50-500 people with the same equipment. The mixer is the heaviest piece.

If I were replacing the rig I would look at the Peavey PR12 speakers because they are even lighter. A powered mixer worth its price will be heavy, so maybe I'd look at the powered Peavey 12's and get a nice mixer - still three pieces. http://www.peaveymag.net/productdetails-dealer-02205-prodid-2629.aspx