Well, if you have to preserve an XP environment to preserve various people's sanity ...
Get a modern desktop system, preferably with an SSD. Install Centos (or other Linux of choice). Install XP and all apps into a KVM VM (using a Linux LV as the XP system's "hard disk").
Advantages: you can make backups of the VM with all apps installed, so recovery after it borks itself is straightforward. (Using LVM snapshot you can do this remotely or automatically, while the XP VM is running). You can use a "network" share for the user's data, and set Linux to work safeguarding the data in it. You can configure firewalling for the poor old XP using Linux. You can be sure it'll never stop working for lack of compatible hardware. Lots of other smaller advantages.
It'll still be much faster than XP native on the old box.
BTW VMware player is slicker and easier and free as in beer but not libre ... and probably not high on VMware's list of things to maintain support for. Which is why I'd recommend KVM, if you would rather put in more effort now than risk handling a problem years down the line when your elderly relative is even less able to adapt to using anything other than XP.
Edit - on second thoughts, probably not an SSD. Lots of RAM so Linux can cache loads without starving the XP VM, and software-mirrored hard disks, so your elderly relative isn't one disk device failure away from losing his sanity. (With smartd sending you regular reports, so you can turn up with a replacement disk drive when it's needed or soon will be).