
There’s no reason why you couldn’t run and test Windows 10 on your 7 machine or vice-versa, using an old copy of Windows Vista on your Windows 10 machine, to test software before you install on your primary operating system.

These days running a virtual version an operating system is practical. Using Windows on a PowerPC Mac was just not feasible apart from testing software. On a single-core machine, this resulted in severe slow-down.


A few years ago running virtualisation tools was a bit of a disaster, particularly when the virtual operating system had to emulate the CPU, graphics card and shared memory with your system.
