I'm interested in building a new system with Windows 7 as the OS. I have a list of parts at https://pcpartpicker.com/user/andy_werber/saved/#view=tn3vjX. My requirements are that the price should be minimal, the processor should run at or above 2.2 GHz, and dimensions of the case be <= 16 inches high, <= 16 inches deep and <= 8 inches wide, but the smaller, the better. My main problem is trying to figure out if I can build something new that will allow installation of Windows 7. I would like to keep the total price below $500. The system would be used to run one piece of software that will NOT run on Windows 8/10, and the cost of replacing the software would be about $1000. Any help would be appreciated, including using better quality components, or adding something (like fans). While I could buy a refurbished machine, it would cost around $250, and I would be concerned that the lifetime of such a machine would be very short.