Cody
Most of us here would suggest the free Malwarebytes for a once a week scan used in conjunction with the free Microsoft Security Essentials for real time free protection. Most here use that combination.
Microsoft Security Essentials is made by the makers of Windows and can be used only with Windows. It is not a one size fits all, like most of the others.
I have not seen one situation where computer problems were caused by Security Essentials. That cannot be said for most of the others.
In addition I would suggest WinPatrol, it is a pseudo Anti Virus, with many, many other good uses. It cannot be used alone as an anti virus, however.