Hello Malcolm,
The two computer model isn't really how PlayIt Live works although a number of other systems take that approach.
Although you can manage the playout computer remotely the split is a bit different.
You will also possibly find that your current hardware is a bit limited for PlayIt Live.
You really have two choices, attempting to get the old system to work again (which may not be impossible) or building a new system, in which case PlayIt Live on a "clean" Windows 10 installation and recent (so built within the last couple of years) hardware with a solid state drive would be a good answer.
Malcolm Hinton