As long as I've been designing PCBs I've always used Eagle Cad. I was first introduced to it in school where the first thing I designed with it was an infrared transmitter to control TVs. When I started at my current company, I found we also used it there to design test fixtures and prototypes. The version I've always used was 5.11, and this was because the PCB machine used at work had a full license to this version. Just to keep things consistent, I installed that version