Many of my clients have been using Windows PC's for a long time and Microsoft is doing something this year that is un-precedented they are offering a free upgrade to Windows 10. If your computer is eligible for the upgrade to Windows 10 it is free. For most home users and many businesses this is a very good idea. Windows 10 seems to be more stable and has better performance on many of the computers I have installed it on. Before you do an upgrade like this make sure your system is backed up and check to ensure that the software you use will work on Windows 10.
Microsoft indicated that this offer is for one year so before July of 2016 evaluate this option.