Well, hello (my first post here, my hands are shaking... :-) )
I've just downloaded and have installed Mach3 on my PC...
I'm trying to find the appropriate SW for my home made simple 3 axis CNC router I'm making... Mechanical part is almost done, electronic part is the next... Before I decide how to make a driver, I have to choose SW because, LPT pinout and wiring to the machine is confused me... is there any default (and changeable) pinout situation picture on Mach www site or in the Mach 2/3/4 program. I dont know what pins are used for IN/OUT (Spindle/Steps/Dir/ENA,Limits). KCAM proggy has a very useful tab in the Setup option says everything about that...
I'll use optocoupled driver. Better to be sure...

You can set the pins to whatever you like (in the range that is valid) You can only use pins 1-9,14,16,17 for the outputs and 10-13,15 for inputs. They are all settable under the ports and pins. Please check out the manual it is VERY good.