Morning Gary and welcome to the forum.
When you originally first got the system was Windows 7 already installed? If so then you may have Windows 7 sitting in a partition which you could use to go back.
If you post the make and model of your system we can advise further.
If you don't have Windows 7 sp1 sat in a partition then you could use the windows.old file. This guide will explain how:
https://support.microsoft.com/en-gb/kb/971760 You will need to do two things in order to use this guide properly. First change the boot order so that the system boots from the disk itself. Second you will need a win 7 disk although your fake version may work just enough for you to pop the legal windows.old version on.
If the disk fails to...