

If older computer that works fine, I’d get a new 780m (Amd) mini pc. They support 3+ monitors, have 2 network ports allowing to “daisy chain” the old computer. No transfering of anything, or worrying about getting old stuff still working.
Deskflow is a mouse/keyboard sharing app. If you keep old computer in sleep mode you don’t need extra keyboard/mouse, but power outages, mean that if you don’t have a floor standing old pc you can stack old keyboard/mouse on top of, then you will need to occasionally plug in keyboard and mouse into old computer to get deskflow restarted (if you don’t put it as autostart).
It’s far more convenient than dual booting. Can use resources from both computers in network, and seemless mouse/keyboard focus. Switching 1 monitor for occasional use is better than dual booting, because rebooting on older computers especially is slow.
Deskflow needs a modern kernal linux distribution. Ubuntu 24.04 is recent enough. Linux mint has not upgraded kernel yet. AFAIU, the only difference between mint (recommended here) and Ubuntu is a slightly prettier version of kde.





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