Anyone who truly knows anything about computers will appreciate that ESET NOD32 and ESET Smart Security are the best antivirus programs out there. Do some research and you will see that they lead all the major players on detection rates, and also on system performance.
That's the great thing about ESET their software is the most secure, but also one of the least demanding on your system - you don't know its there.
Easy to install, and now I wouldn't even know it was running on my machine! Previously had Norton Internet Security running, but decided to switch to another product to get a smaller footprint on my memory as my machine didn't run as fast as it should. My Toshiba laptop is now running much faster, and most likely, more secure then ever before! ESET Smart Security is worth every penny and works brilliantly on Windows 7.