Re: 5% of 1000 000 is 50 000 desktops.
I don't work in health, but in research and I expect the issues are the same.
There are pieces of technical equipment which do a perfectly good job and do not need replacing, but which have legacy hardware systems and cannot be upgraded or run from a modern (Win7 plus, or MacOS10) PC. These are often very expensive pieces of equipment (my own personal favourite was a half-million dollar MALDI-TOF Mass Spec which was running on NT) that you just don't toss away when MS or Apple stop supporting the OS.
I am sure that in some cases there is lack of proper upgrading, but you don't replace equipment worth hundreds of thousands of dollars (or pounds) on the same frequency that you replace PC or operating systems. Be as outraged as you like, but then calm down and look at the real situation - it is legacy hardware that is still running old versions of the OS and an upgrade is simply not available.