I've been looking for a antivirus that's really lightweight and offers good protection. I'm currently using Microsoft Security Essentials and Malwarebytes (only when I really need it). I've seen that many sites say that Avast is the most lightweight on RAM usage, but I didn't find any reliable information on CPU usage. I've also seen some people say that Essentials is the most lightweight, which got me very confused. The specs of my laptop are (really bad):
OS: Windows 7 Ultimate Service Pack 1 32-bit
RAM: 2GB DDR3 Single stick (but it's configured to dual channel) 1333MHz
CPU: Intel Celeron 925 2.3GHz Single core, No Hyperthreading
(i)GPU: Mobile Intel GMA 4500MHD, PHDGD Quebec 4.0 drivers Dedicated memory 128MB, Shared memory 749MB, Total memory 877MB
OS: Windows 7 Ultimate Service Pack 1 32-bit
RAM: 2GB DDR3 Single stick (but it's configured to dual channel) 1333MHz
CPU: Intel Celeron 925 2.3GHz Single core, No Hyperthreading
(i)GPU: Mobile Intel GMA 4500MHD, PHDGD Quebec 4.0 drivers Dedicated memory 128MB, Shared memory 749MB, Total memory 877MB