I've an old Panasonic CF27 that is only limited by my not yet replacing the RAM with a larger stick. It still runs just fine with win98 or most any low resource non Microsoft platform. I've also heard tell of old Dos machines still running along perfectly performing there business function. I've also installed a few old Dos machines when I was working for a value added reseller; how much machine do you realy need for a point of sale?
At some point, hardware does stop supporting modern functions but it's much older than most people realize. If your willing to put down the Windows pasifier and bottle, older hardware will run just fine for most people's uses.
New hardware is only required for truly resource intensive tasks such as gaming, autocad and the like. The needs that finally pushed me to upgrade where modern video games, running more than three VM at a time without slowing the machine and a personal need to learn and explore the limits of newer hardware. In a business, I wouldn't toss hardware if there is still any possition it will support.
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