Warning for Windows XP users buying new machines - Hard Drives now 'Advanced Format'.
So, further to my earlier post querying these new '4k' and '512e' drives, it appears that at least one manufacturer is now no longer shipping the old style hard drives - Dell. According to my supplier, hard drive manufacturers have EOLd pretty much all 512byte drives.
This will cause issues that need to be overcome for XP users, and also cause issues with imaging.
So, if you haven't done so already, read up on them, as they are here to stay, and as was suggested to me - look at moving to a newer OS.