With Windows 7
Antivirus - MSE or Avast (make sure the other is uninstalled properly as only one antivirus should be used
Antimalware - Malwarebytes free - (scan weekly)
You can also use SpywareBlaster as a blocker
Be careful of registry cleaners as they can often cause more problems than they will solve the only one I would recommend is built into CCleaner which is very good for clearing out rubbish and deleting internet history.