I want to tread lightly here, but Gecko G540 is not necessarily your best choice looking to the future. Don't get me wrong, I own 4 of them. Ferris/Farris (sp?) the owner/inventor of the Gecko line is a great guy and offers free/low cost repairs for his products. But there hasn't been much development in the Gecko G540 for a while and it is pretty much tied to use with Mach3, which is also lacking in new developments. Further, Mach3 is designed to be used with a parallel port. Unfortunately, Microsoft has abandoned support for parallel ports, so parallel ports don't exist on new computers. (Or maybe PC's abondoned LPT1:, so Microsoft followed suit - I can't say for sure.)
I am running Mach3 with a parallel port on a computer running Windows 7/32 bit. That is the most modern Windows OS you can use with a parallel port. Beyond that, you can use up to Windows 10 with a Gecko G540 and Mach3, but you must add a SmoothStepper or similar replacement for that parallel port. Again, I own both Mach3 and Gecko G540 and use them, but I have been exploring newer options.
There's a lot of buzz about the Leadshine controllers. I have to admit I don't know which software is recommended for them. I've also been looking at the Acorn CNC controller and the Centroid software. There's a lot on YouTube about them.
I hope you find some of this information useful.
Gary