Are you looking for a free antivirus or a pay antivirus?
Also, is this for your Windows 8 computer or your XP?
The answer to your question may vary depending on whether you're looking for a free antivirus or not, because some of the free ones don't do a good job removing viruses while the pay versions work fine.
Microsoft Security Essentials is a free download for Windows 7 and Vista. But on Windows 8, Security Essentials has been renamed to Windows Defender and is part of Windows (Defender on Windows 7 and earlier was a different program). So with a Windows 8 computer, all you need to do is make sure it's running and has been updated. I've noticed that Security Essentials updates daily by default, while Windows Defender on Windows 8 notifies me that it needs updating through the security icon in the taskbar, but doesn't update automatically.
I think Draclvr often uses Security Essentials (called Defender on Windows 8) along with MalwareBytes on the computers she services, which is what Barry is doing.
If you're looking for a low price solution, this works well. The pay version of MalwareBytes is $24.95 per year
https://store.malwarebytes.org/342/purl-consumer?x-source=websiteThey have a free version with links to both on their homepage
https://www.malwarebytes.org/Here is the difference between the free and pay versions:
https://www.malwarebytes.org/antimalware/