I installed windows 10 to give it a try after all they do say if you don't like it you can switch back to windows 7 (etc). I tried it didn't like it and clicked on the roll back button.
during the roll back it somehow corrupted several files and broke the main frame.
a week later and somewhat out of pocket after a vist to the repair shop I'm back on windows 7.
the repair guy installed something on my laptop to stop windows 10 from installing its self.