Two options really.
Boot it into safe mode (with networking) and while in safe mode, disable system restore, install malwarebytes, let it update and then run a full scan and see if that gets rid of the problems (psecurity.exe is a rogue anti virus program BTW)
Or,
If you have the media and the owner has all personal files backed up, do a full reinstall. This will have the benefit of clearing the infections and getting rid of all the crap that is always installed on new laptops from the factory. If you do decide to do a reinstall then remember you'll also need to download all the latest drivers for all the hardware from advents website, make sure you install a decent anti-virus program and also run a full windows update at least 3 times (keep running it until it's got nothing else to install)
Personally I would go for the latter option, it's not the quickest or the easiest but the system would be left in a much cleaner state at the end of it.