I have read the threads on using 64 bit OS with Mach3 and understand the points made with great patience by Art.  The parallel port cannot be used on a 64 bit system.
I want to use Mach3 in demo mode so that I can test G code programs, because I have W10 indoors where it's warmer but the licensed version running on XP is in the workshop where it is currently less pleasant.  The demo version does not install the parallel port driver - so I should be able to install it on a 64bit W10 machine.  I  haven't had much success in achieving this so far - am I missing something here?

What problem are you having? Lots of people are running machines with mach3 in Windows 10. (with motion controllers)

Thanks for the quick reply.  The problem is that the installation doesn't complete.  The installation reaches a point where it displays "Installing files...Seeking" and shows progress bars continually running across the screen.  After about 30 minutes without change I have to cancel.