I have been using Microsoft Security Essentials on all my Windows machines. It works great and stops all virus infections. It is free for small business and personal use. In comparision to other products – including paid products this comes out on top.
It works great on low powered Windows machines. It is free and can be downloaded from here with a genuine Windows Operating System.
From their website:
Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
Microsoft Security Essentials is a free* download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It’s easy to tell if your PC is secure — when you’re green, you’re good. It’s that simple.
Microsoft Security Essentials runs quietly and efficiently in the background so that you are free to use your Windows-based PC the way you want—without interruptions or long computer wait times.
Learn more at the Microsoft Malware Protection Center
Find information, definitions, and analyses of all the latest threats that Microsoft Security Essentials can help protect you against in the Microsoft Malware Protection Center.
Need security for your business?
Microsoft Security Essentials is available for small businesses with up to 10 PCs. If your business has more than 10 PCs, you can protect your computers with Microsoft Forefront Endpoint Protection.
*Your PC must run genuine Windows to install Microsoft Security Essentials. Learn more about genuine here.
You can download the application from here.