We use Digitrax Digital Command Control for our layout.  The command station, show below, has a DCS100 command station, and three DB150 boosters.  We use four Model Fuel Tanks from Loy's Toys as power supplies for each unit.  As you can see from the photographs, the command station also has air moving fans and air filters to keep the heat sinks cool.  On the layout we use 14 PM42 power management units to establish smaller power districts and for automatic reversing sections.