With more flexibility, you have more chances to make your own mistakes.

Kit without the windows tax is inherently less expensive, what you do with that kit is your decision, informed people know you can run new systems using less power and have it cheaper, it is not a choice of shiney new WHS versus some old box.

Oh, and you are deluded. my 30W single-drive fileserver is modern, but even my gaming rig doesn't use close to 350W so get your facts straight.