Not sure why XP support should be and issue at all. It is the most stable OS for this application at present, and, as I said, if you're planning on using the same PC for other purposes, you're asking for trouble anyway. Not being able to "buy" XP is a non-issue, as you can easily buy a machine that has it pre-installed, which gives you a valid license, so why would you ever need to buy it? 64-bit offers nothing of value in this application. Again, you're more likely to create problems for yourself, and there's nothing to gain to offset that risk, so why do it? "Most users are going to 64 bit...."?? On what do you base this? I know very few people who've gone 64-bit, and those few are using big-memory applications - PhotoShop, commercial CAD programs, and other things where it's needed. There's absolutely no need for it here. You'll be one of a VERY small number of people using the setup you're suggesting, which almost certainly means you'll have problems that nobody else has, and fixing them will be a low priority for the developers. Makes no sense to me, when XP is cheap, stable, available, and has been proven to work well by 99% of the Mach3 user base.
Regards,
Ray L.