At no Cost.
Remove MS Security and install AVG, Avast or one of the other Free Anti Virus Programs.
Also a Free Firewall, Zone Alarm or Comodo.
As well as CCleaner you will need at least one of the Free Anti Malware programs, I would suggest Malwarebytes or SuperAntiSpyware. I use Spybot S&D as well, but many people don't like it as they find Tea Timer, it's Resident Protection, intrusive.