I have had an older "workstation" around my house in non working condition for about a year now. I got it for free with a 250gb HDD, Core 2 Quad Q9550, and 8 GB DDR2 RAM. It is a Dell Optiplex 960.
Today is my brother's birthday and I have been thinking of working on it to get it into good condition, I took all the parts back together and assembled them with a different 500 GB HDD. The 500 GB HDD I got from a SFF HP RP5800 and is kinda known for fucking up Windows. It is my best bet, I know my brother doesn't want anything under 500 GB since that is what his laptop has right now. This PC would be a huge upgrade for him. The 500 GB HDD right now has a bunch of word documents from my mom's old hotel and a fucked up Windows 8 install. I popped it into our current machine to look through it, back it up, and such. If I clear everything from the HDD (I also need to know how, I have tried before and Windows doesn't like you to just right click and delete System32) and put on a Windows 10 installer, when I boot it up would it go to a Windows 10 install screen? Also, on a $50 budget, what do you think I could get for a GPU for it, right now it has an old ATI X700 Pro (256 mb) in it that I have been trying to sell.