What hardware to choose for virtualization of four viewers?

Question

Virtualization

It's more like a daydream (for financial reasons)
Three internships in adjacent rooms. In two by one, in one there are two viewers (multivox 3d) on Windows. The doctor downloads the picture, adjusts and looks at it (describes it), if he writes something, then on another PC (two keyboards and two mice on the table, there is no CVM yet). The pictures themselves probably lie in the video memory (textures). If CT or MRI will scroll, but this (I think so) is just a change in textures (the video processor is working). There are three-dimensional modes, there maybe something is considered on the processor (the video cards are weak, but most likely they can use OpenCl, it would be on something). I haven’t written or measured loading analytics (graphics) yet, but it seems that most of the time they just stand there. Processor 2-4 cores, Ram=8GB, HDD/SSD >20GB, cards {EN6600SIL,Quadro FX1700,HD4850,...).
Two PCs - WindowsXP 32, two remaining Windows7 64. There are few tables in the staff rooms, there is even less space under them. Switching jobs via KVM would be very convenient. But I don’t want to make a closet with computers in a technical room :) Although it’s convenient to vacuum them then, I tucked the shoelaces and the vacuum cleaner ...
I want to run them with virtual machines (dream).
1. Launched WindowsXP for testing (n3050, 4 cores, 8GB RAM), feeding it a virtual disk (tempfs), where I set the paging file and data for processing. The speed has increased a lot, and there is no recording on the SSD.
2. Each machine has one disk. You can put an SSD, but Windows spins 1.7GB of the swap file in its corporate style, I'm afraid they will die quickly. If you turn it off, it will not allow you to open more than one or three pictures :) It slows down, including on the disk due to the paging file. I do not want to make a sacrificial SSD. If you virtualize, you can make a raid, remove the entry on the SSD.
3. I heard, but I haven't tried it myself - load virtual machines from the image, but write changes to a separate file. It turns out as windows-pappyrus. Each user can make their own DIF file. It turns out a good saving (?) of disk space, if it (20GB) in RAM is a quick reboot (which is necessary many times a day), you can try already downloaded "images" instead of rebooting ...
It turns out for one virtual machine:
8 GB - memory.
2-4GB - paging file.
You need 4 of them (without a reserve for jumping on reboot) - 40-64GB of ram. You can turn on "ballunning", but they are probably rebooted due to memory leaks, and it's not a fact that Windows7 will "give" a free one.
It is necessary to install 4 pieces of video cards, at least in 8th mode. Each user (two monitors) is connected to their own video card.
And a lot of memory. The processor can be 2-4 cores to start.
The catalogs have:
TR4 ---- 128GB RAM.
MB- 23t.r., CPU - 27, RAM (32G * 2) 24 * 2. In the dream list, a toy is obtained for 70 thousand rubles. :(
AM4 ---- <=64GB RAM.
Prices are slightly lower.
Who will advise what hardware?
Does it make sense to look at old servers, server boards (without cases)?