This certainly wins for lowest cost, but I don't think it wins for lowest environmental impact - the spares reduce much of the benefit If the author makes it t

This certainly wins for lowest cost, but I don't think it wins for lowest environmental impact - the spares reduce much of the benefit If the author makes it to 10 years with these 3 laptops from 2006, it will add 3.3 years of lifespan to each laptop. Assuming the prior owners used them for 3-5 years, this endeavor extends the lifespan per laptop to 6.3 - 8.3 years, so I think buying new in 2017 and running with it until 2027 wins in terms of useful life per laptop. I don't know if the energy usage of operation over 10 years is significant compared to the energy usage of manufacturing, but a 2017 laptop would be dramatically more efficient than a 2006 laptop (assuming the same software running on both).