first of all that was cringey as forget:second this belongs in PC megathread
If your on a budget a GTX 750 ti will do good, but if you can go higher go for a GTX 970.I really recommend you build one yourself, I learned through YouTube tutorials.
I know people have already said this, but you're much better off building a PC yourself. Not only do you get more for your money, you also get more control over what parts are used other than the CPU and graphics card, such as the power supply, SSD and hard drive. Here's one I put together for you: http://pcpartpicker.com/user/Chipskate/saved/pxNH99
He should get windows from the microsoftsoftwareswap , its way cheaper, and just download the windows 10 iso, since he can activate windows after its installed.
Oh right, forgot that was a thing. Yeah, that's definitely a better alternative than buying Windows 7 and then upgrading to Windows 10; cheaper and less of a hassle.
I made my own list i want you to check it please http://pcpartpicker.com/p/FMyPqs