Do you absolutely have to buy Mach 3?You could download LinuxCNC which is absolutely free and more up to date than Mach 3 .If you are unfamiliar with Linux and a bit hesitant to move from the Windows ecosystem please be aware that the download can be burned to a blank DVD which you can try in your computer by adjusting the boot sequence to boot from the DVD drive and having the live version will allow you to look around and see whats there.You then shut the computer down and it acts just as it did before.If there is enough space on the hard drive you can even make it a dual boot machine with the choice of Windows or LinuxCNC as the operating system.I did this with the venerable desktop box that runs my home made router and actually found it easier to run the Windows version of F-engrave under Wine than the native Linux version.Never lose sight of the fact that its all 1's and 0's and they all taste the same to a stepper motor.

You may be advised that a laptop isn't the best option for running a CNC machine and I expect thats true.The Vista era Dell that runs my router cost me £28 for the base unit and monitor and uses a spare keyboard and mouse I had gathering dust.The fastest way to get cutting would be to buy the dedicated software and learn it.