Newb Intro

First sign on, new to Linux, completely lost. Until last week I spelled Linex wrong, so that is how new I am to it.
I want to put Linux OS on an old Windows computer and load LinuxCNC to run a desktop milling machine. It has been running on Mach3 but that computer died and I lost my files. I have dabbled with Arduino and RP4 2G and have fair set of skills for computing, but would like to know from the experts what the easiest approach would be to use LinuxCNC. Should I load and run from a desktop with parallel port or should I set it up and run it with a thumb drive from RPi.?
Fishbone

The easiest road is going to be using a PC. If your old machine was using the parallel port, your simplest way to connect would be to use the parallel port again. If you can find or come up with a copy of the XML configuration file you were using with Mach, it is possible for Linuxcnc to import that and automatically read most of the old Mach settings into the new Linuxcnc configuration. (Saves you from having to figure out the old pin assignments and axis scale settings.)

If your old setup was not using the parallel port, and or you don't want to use the parallel port, you will need to buy some other interface hardware, such as something from Mesa. While that stuff can be very nice and high performance, if you're machine is only of parallel port caliber, it is kind of wasted money to buy high performance interface hardware and will add more complexity to setting it up.