After my experience with a friend PC I would say stay well clear. Sparktrust suddenly appeared on her PC on start up. Confusing Sparktrust with Ccleaner she let it run. only to be confronted with a message saying she had several hundred problems and that it would cost for the program to remove these problems, so she closed the program down. She then found that she could not run any programs, so she restarted he PC only to be confronted with the same message. That is when she asked if I could help. I started up the PC in Safe Mode, but after a few seconds the PC shut down. Eventually I reformatted the PC as it was the only way to go with my limited experience.
There have been many instances of people downloading a free programme with this sort of result. My advice is, if you come across a programme that you are in the least bit wary of, then do a google on the application BEFORE doing anything else.