The Windows 10 machine can definitely use the One Core voices. Up through Version 1809 you have to download them as part of language packs. I have been told that this will no longer be necessary as of Version 1903, but haven't played with that yet on my one machine that's got 1903 on it.
I haven't touched Windows 7 in years now, so I'm no help there.
Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763
Puritanism: The haunting fear that someone, somewhere, may be happy.
~ H.L. Mencken