Microsoft provides free antivirus and antimalware for Windows users, with the Microsoft Security Essentials pack.
It claims to be light weight and will not consume much of the system resources for scanning and updates. I have installed Microsoft’s Antivirus along with my Kaspersky Internet Security, and both are working happily without hogging the system resources.
Download Microsoft Antivirus and Antimalware for your Windows based PC/ Notebook.
Related: MS Word Keyboard Shortcuts | MS Excel Keyboard Shortcuts | Party invitation templates | Windows 8 User interface | Google Spreadsheet Keyboard Shortcuts