After a short three-month beta program, Microsoft is officially releasing Microsoft Security Essentials (MSE), its free, real-time consumer antimalware solution for fighting viruses, spyware, rootkits, and Trojans. MSE is yet another layer of defense the company is offering to help its customers fight the threats that plague Windows PCs.

Microsoft Security Essentials is available for Windows XP 32-bit (8.61MB), Windows Vista/7 32-bit (4.28MB), and Windows Vista/7 64-bit (4.71MB). The final build number is 1.0.1611.0. Microsoft warns that MSE should not be installed alongside any other antimalware application. Indeed, MSE's installer disables Windows Defender completely, which makes sense as it is a sort of superset to Windows Defender. It builds upon Windows Defender by offering both real-time protection and on-demand scanning for all types of malware.

Although you won't be asked for personal information or to register for anything, you'll need to pass the Windows Genuine Advantage validation to install MSE. In short, while Microsoft's security updates are available for free to pirates, active protection from Redmond isn't.

One might notice the "Essentials" branding that Microsoft is clearly pulling from Windows Live Essentials. MSE won't be included in WLE, however, even though non-Windows Live applications like Silverlight are included in the suite. Furthermore, there is no download link for MSE included in the final release of Windows 7, but there is for Windows Live Essentials. This is a curious decision given that Redmond wants to push MSE out to all those who currently do not have a security solution (between 50 and 60 percent of Windows users, according to the company). Nevertheless, it can be quite easily explained: Microsoft wants to avoid antitrust issues from competing security giants.

Now that you've got the necessary background information, let's take a closer at the different features of MSE.

The GUI

Microsoft Security Essentials has one of the simplest and clearest GUIs we've seen for an antimalware solution. This is not something we would call "obtrusive" or "bloated" like many of the security products currently on the market. It may not be the most elegant design, but that's not what one should be looking for in a security solution anyway. An antimalware solution needs to clearly communicate important information when you're using it; barring a need for user response, it should make itself scarce.

When everything is running as it should, MSE makes sure users know all is well, with a green-colored highlighting across the UI and via a green taskbar icon.

When something is amiss, MSE makes sure users know they'll need to take action, with red-color highlighting across the UI and via a red taskbar icon.

Microsoft Security Essentials updates itself very quietly in the background. In fact, we were never once bothered by its updating system; the only prompts we received were when the application actually needed our attention, like when it detected a threat that needed to be cleaned. Signatures are updated more or less daily through Microsoft Update, though new signatures can be published as often as three times a day. The core antimalware engine is scheduled to update itself with new features and bug fixes on a monthly basis.

The History tab is useful for reviewing how well the program is working, and tweaking decisions you've already made on previous detections. It gives a great overview of what the program has found and also gives more information on each potential threat.

MSE has a surprising number of settings to work with. Considering the simplicity of the product, it's still very customizable. Power users enjoy having tons of features to tweak, and we think they'll be satisfied with the settings that can be changed in MSE. It doesn't offer as many options as some other security suites, but given its features, the settings that can be adjusted are exactly what one would expect.