There are a number of ways. If you have another drive You can copy all your data (not programmes). I use Freefilesynch and do this often. It will use the same as the amount of data, and in my case I have it all on a separate partition. For the system (C:/ drive - Windows & and all other programmes) I recommend a free programme : Macrium Reflect. Make an Image and it will compress the back up. You can even choose a higher compression. If your drive is not partitioned it will still work.