I recommend windows 7 professional. Also windows 7 lite which cuts out some components to make it faster than other versions. They are the best operating systems for that processor and memory. They give you speed and stability in the operation of the programs. Better yet you can install a new solid ssd disk to boot the operating system and you will have an arrow. And you leave the normal hard disk hdd for the other programs photos, music and videos. I hope I have been able to help you. :)

If you like windows and want to continue to have support and security the best option would be windows 8.1 as this is more optimised than windows 10 or you can also look for a linux distro