Which means by buying these workstations used and on-the-cheap, I'm polluting less than if I were to buy brand new hardware.

Then there's the electricity cost. I own quite a few old workstations like this, and the power consumption ain't that much higher. Yeah, maybe compared to a laptop, but that's like comparing the feeding habits of a hummingbird v. an emu (and you can buy old laptops for relatively cheap, too).