This month the free windows 7 or 8 upgrade to Windows 10 expires. Is that really important to you? Maybe not.
If you just now just now decide to do the upgrade, here is an important tip.
Have in place a Backup Plan.It can be another hard drive, a stack of DVDs, a big USB thumbscrew or even another PC. with extra drive space. After you have installed Windows 10, you can use your backup to revert back to Windows 7, if need be.
Here is an article explaining how to backup before you do Windows 10.
How to backup your PC before upgrading to Windows 10 By Graham Barlow September 16, 2015
While it's highly unlikely that anything will go wrong in the course of an upgrade, we'd still recommend being safe – a new install is a good excuse for a backup! If you're heading for a clean install or an upgrade, you'll want to make sure you don't lose anything valuable in the process
Also, some free cloud storage services will give you enough space to backup a stripped down version of your current OS.