Hi,
Mach's parallel port will only run on 32 bit Windows 7 and earlier PC's. So yes, get another XP PC if you can find one.
Mach will run quite happily on a Windows 10 or any 64 bit OS but you MUST use an external motion controller.
There are plenty of them, one of the most popular is a UC100. It is USB connected to the PC and has a familiar DB25
plug output. You might say it is a USB to parallel converter but that is doing it an injustice, inside it has an FPGA and is way WAY
too smart to be called a converter, its a genuine external motion controller. They are about $120. Don't buy a cheap (Chinese
knock-off) one off EBay or Amazon, get the real deal or don't bother.
While USB works its prone to problems, Ethernet connected external controllers work better. Additionally the UC100 has one parallel
port equivalent output, ie 17inputs and outputs. If you go with an Ethernet connected controller like an Ethernet SmoothStepper it
has 51 IOs, a 57cnc has 57 IOs or a UC300 has 85 IOs. So you can have alot more IO if you wish.
I use and like an Ethernet SmoothStepper by Warp9TD at $180. It has a mach3 AND a Mach4 plugin so you can upgrade to Mach4 if you wish.
I have used Mach4 for six years now and its streets ahead of Mach3 in my opinion.
Craig