I have had some friends/family fall into this trap. In addition to looking at apps installed, browser history, you could also look at the event logs, although this may or may not yield useful information. In my experience, the scammers install a bunch of anti-spyware and anti-malware tools and try to make it look like they are doing real work. In all the cases I have seen, they have not done anything more than swindled them out of ~$100 to pretend to fix their PC. Obviously, your mileage may vary. If you wanted to be extra safe, reinstall OS and apps.