G2A is good as well for getting a OS
https://www.g2a.com/windows-8-professional-32-64-bit-cd-key-global.html
I think I get my Win 8.1 for maybe $18
Its a lot now but it going up and down. You will just need a boot disk or some thing.
I was on the web and i saw this gem...
http://www.etsy.com/shop/8BitMemory?section_id=6678855
I do not know if this is on the forums but I think it would. If not it is now.
I have been having to same thing go on, but at one it ran so well on max. Then one day tried to play and get very low FPS. All be it my rig was new with 4 or 5 things on it. What do you think is going on?