I'm going to disagree with all who recommend upgrading to windows 10. No version is worse then 8 or 10 for actually doing any real work. They are great for being flashy, looking good, and maybe playing games and such but try and customize it to your liking, fixing problems, running basic programs are so much more work then 7 or earlier. I would rather continue running XP before 8 or 10.
While being current has its merits, such as patches, security updates, etc. One can also weight the odds of getting "hacked" and see that you can probably play and win the lottery more often. While large corporations have more incentive to stay up to date and on top of security patches due to be a larger target, us little guys or personal computers don't really "need" too. Just a little common sense and a decent antivirus software will keep the bulk of us safe.
But in the end, it is all personal preference