Malwarebytes.
Microsoft security essentials.
Ccleaner.
I once got a virus, my parents paid some guy to fix it, and these are the programs he installed.
They all work wonderfully.
Security essentials can do 24/7 monitoring and scheduled scan.
Malwarebytes can get rid of viruses security essentials cant.
And ccleaner can delete temporary files to speed up your computer, fix registry issues, and delete/uninstall ANY file you want.
And they're all free.