I suspect that he is running Windows XP for a reason.
1. Most doctors are not that tech savvy, though they think they know everything, and perhaps he is happy with XP and has had no problems.
2. Perhaps by continuing on XP, he doesn't have to comply with certain sections that allow the bureaucrats to dictate, a la 0bamcare statutes, the treatment and (most of all) the reporting requirements; or
3. He showed the idiot media some old PC that was sitting around in case they got a little to nosy.
There may be another possibility: Trump may have tipped him off to Microsoft’s “snooping” capabilities of the later versions of Windows, and suggested he stay with XP.
His file servers may not be XP. Just cause he has an XP on his desk does not mean patient records are stored on that specific computer.