Microsoft products are notoriously full of security holes, but as an industry we've come to accept and deal with that. Even Microsoft has conceded the issue, launching its own security tool, Windows Defender (based on software it acquired from a company called GIANT AntiSpyware), in late 2006.

Kudos for being proactive. The only problem was that Defender was functionally useless. Regularly relegated to also-ran status in product reviews, Defender simply didn't seem to do anything. In my experience it was completely helpless at discovering or removing anything beyond the simplest of malware infestations.

As a result, Microsoft announced it would discontinue the program last year as it worked on a replacement, and that replacement, Microsoft Security Essentials, is now available as a beta, beginning today.

Based on its OneCare product, the new Microsoft Security Essentials, or MSE, is a free offering, but you'll have to go through some hoops to get it. Click the above link, then click "Get it now." You'll need a Microsoft Connect account (which in turn requires a Windows Live ID), and you'll have to answer some survey questions about how you use your computer. Software validation is also required along the way. Eventually you'll get to a page where you can download one of three versions of the software, an XP version, a 32-bit Vista/Windows 7 version, or a 64-bit Vista/Windows 7 version. Download and install like you would any normal application.

Reportedly this beta is limited to the first 75,000 downloads (though there's no mention of that on the MSE download page), so you might want to download it quickly if you're interested.

MSE (formerly known under the code name "Morro") offers real-time scanning for viruses and spyware, and, mercifully, a dead-simple interface. It's actually far more difficult to download than it is to use, and while I can't comment yet on how effective it is at scanning for security problems, it does at least do a thorough job of scouring your file system for them. Scans proceed relatively quickly, and status updates are clear and easy to understand.

Is this a replacement for the antivirus software you're running right now? I wouldn't uninstall your security program just to run this one (and remember, don't try running two security suites simultaneously), but if you're currently without a security package, this isn't a bad one to try out (it's free, after all) -- as long as you remember you're really a beta tester.