As I’m sure you’ve heard by now, starting on July 29th, you’ll be able to upgrade your Windows 7, 8 and 8.1 PCs to Windows 10 at no charge. But there are a couple of things you should do to get ready.
Windows 10 will need at least 16 GB of free hard drive space to install. So if you don’t have that much room, you’ll need to think about getting rid of some unnecessary programs or moving some space-hogging files to an external hard drive. This is exactly the same about of space required for Windows 7 and Windows 8 (and actually a little less than the 20GB required for 64 bit installation in these systems)
To check how much space you have available, type Computer into the search box in the Windows 7 Start Menu or This PC in the Window 8.1 Search Charm and click on the result. The amount of free space on your main hard drive should be displayed right beneath it.
When you install Windows 10, it should leave your files and programs intact. But it is still a good idea to back up important documents before you install.