Windows new build

[coa9991]

I recently built a PC in a mini ITK form factor, but I just transferred the Windows ISO image from my laptop. I found out later that OEM Windows copies are only valid for that machine, and only store-bought copies can be transferred.
Is it worth buying a new copy though? It works well enough, and can play all the games I want from it.
When is a good time to upgrade it, since there would be the usual upgrades from MS?

 

[Deleted member 77746]

I recently built a PC in a mini ITK form factor, but I just transferred the Windows ISO image from my laptop. I found out later that OEM Windows copies are only valid for that machine, and only store-bought copies can be transferred.
Is it was buying a new version though?

OEM = Tied to the machine purchased (if built then to the initial components)
Retail = Can transfer licence from machine to machine.