To cut a long story short.
Although Microsoft say that they are still supporting Vista, the manufacturers have started dropping it already. There are officially no XP/Vista drivers at all for some of the new motherboards that are on the market.
If you buy one, and then plug your HD in you will be asked to obtain a new id for the OS. Do this and you have a legal copy of the OS. At that point you cannot use XP/Vista anymore as you will have linked the OS to a motherboard that does not allow it to run with any drivers.
You can't switch back to the old motherboard as you have just changed the id.
In short you have a brick by design.
My advice to anyone is to do what I did. Before you take a single screw out of your pc, download Linuxmint and create a bootable USB stick. You can run the whole of Linuxmint from the stick, you can install Linux from the stick, and you can read the Windows files from the stick, or from a Linux installation. It is a very simple click, click, click process and takes mere minutes from start to finish. It is 100% free, and it works just like Windows.
Linuxmint has free office software included with the download, along with media players, software manager etc. All software is free and is simply downloaded from a simple screen within Linux, search and click, a bit like the Play Store, except everything is totally free.
You can then either drop Windows altogether as I have now had to do (not my choice - Microsoft dropped XP/Vista customers when they gave all their other customers W10 for free, I won't get stung like that again).
I have no idea what sort of marketing strategy Microsoft have embarked upon, but isolating and kicking one group of people who bought their product for no good reason, whilst rewarding others, is one hell of a way to run a business.