I'm new to this PJ game so I'm trying to find out as much info as I can. Now, I keep hearing about the Quadscan and the Iscan, but what do they do? What is the differance between the two? Do they both line double? I think one is a Scaler(Quad), if so what is a Scaler? Do I need one? (with a CRT) Which is better? Feel free to help, Please!