That's not as blazing fast as some of the paid suites, which can complete installation in less than 60 seconds, but it is respectable for a free program. Overall, the installation time ran around 4 minutes on our test computer. It also lets you choose whether to run the Windows Defender firewall, and whether to run a scan once installation is complete, although both of those are opt-out. Microsoft politely does not opt you in to the program's customer experience improvement program you must choose to opt in or stay out of it before you can finish the installation. It takes very little effort to get going with MSE. Security Essentials has begun to mature, although it's still rough at the edges. Version 2 introduces deeper hooks into Internet Explorer and the default firewall in Vista and Windows 7.

Now in its second iteration, Microsoft Security Essentials (MSE) debuted as the lightweight, cloud-based successor to the paid security suite Live OneCare in 2009. However, its impact on system performance could be improved, and it's still a bit light in the tool belt.

The bottom line: Microsoft Security Essentials, an antivirus program created by Microsoft, will protect you, and it will generally do it well.