I strongly recommend avoiding McAfee. They have a long history of providing inferior products. Instead, consider the free versions of either Avira, Microsoft Security Essentials, AVG, or Avast. Just one of those to have a real-time scanner. Then follow that up with the on-demand programs Malwarebytes and SuperAntispyware, which you should update and do at least quick scans on once a week.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.