On Thu, 14 Jun 2018 18:22:11 -0700, Newgene McMensa wrote:

I just picked up "new" OEM versions of XP and 7.

What do you mean by 'new'? OEM versions of Windows XP & 7 still need to be
activated on-line with Microsoft. Usually, the MS server will refuse to
allow it if the hardware config does not match that of the previous
activation for that licence.

You might have success if the licence was never activated, is that what you
mean by 'new'? If so, there might be other problems; sometimes MS provided
OEMs with 'tinkered' versions of the OEM install that would only work on a
host with a specific configuration.