I am long term friends with owner of Computer Services Nottingham. If my Mach 3 PC crashed, I would get an old machine for free, that somebody has traded in and load it up with my software from the mirrored NAS box. I speak from experience. That way you get a PC good enough to run the fairly low demands of Mach3 and with a parallel port.

My systems are all networked and the Mach3 machine has the Internet Gateway disabled, so no stupid interruptions. All my Gcode is generated on my Win10 machine and filed in the NAS box, so a hard drive failure on the CNC machine has low impact.

Even my 3D Printer has a Wifi enabled SD card, so I can download to it easily.