After many years of trying to support Mac gaming by buying only Mac games I am finally biting the bullet and getting Windows for my Mac Pro, mainly to get Planet Coaster and realizing that Apple will never update OpenGL again. Some questions... 1. I have my dad's Windows 7 pro DVD that I am guessing is an OEM disk that came with his computer. It is white and says "Licensed for use with the registered refurbisher program. registeredrefurb". Can I use this DVD to install Windows if I buy a license key online? 2. If yes to #1 where is a good legit place to buy a Windows 7 key? If no then where is cheap place to buy Windows 7 pro DVD? Ebay brings up confusing results, with some auctions saying I can't install on Macs. Odd. 3. How much would you recommend for the Windows partition? My SSD has 396GB free space. I won't be getting too many games for the windows side as I will still buy Mac games when possible. 4. Is there any gaming features I would be missing by getting Win 7 over Win 10? Will Win 10 even install using bootcamp on my 5,1 Mac Pro? Apple says my Mac Pro is not supported, and I am trying not to pay $120 for Win 10. PS - I am using a non-flashed PC nvidia GTX 670, so whatever I install I need a way of switching back and forth from MacOS and Windows without a bootscreen. Thanks.