The bottom line: Microsoft Security Essentials 2 will protect you, and it will generally do it well. However, its impact on system performance could be improved, and it's still a bit light in the tool belt.
Review: 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. Version 2 introduces deeper hooks into Internet Explorer and the default firewall in Vista and Windows 7. Security Essentials has begun to mature, although it's still rough at the edges.
Overall, the installation time ran around 4 minutes on our test computer. 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.
MSE 2's interface adopts a different color scheme than the previous version, going for various shades of gray to replace the vibrant blue and white look. It doesn't pop as much, but it also looks far less like a Windows XP relic.
For those unfamiliar with the design, MSE has four tabs across the top. The Home tab contains your security status and scan options, and you can run a Quick Scan, Full Scan, or Custom Scan. A link at the bottom of the pane lets you change the scheduled scan.