Trend Micro Antivirus + Antispyware ($40 for a one-year, single-PC license as of 11/17/2009) came in last in our roundup of stand-alone antivirus software, weighed down by comparatively poor malware detection, slow scan speed, and a seriously misguided habit of hiding what it does from the user.

In traditional malware detection tests conducted by AVTest.org, Trend Micro was able to detect 96.9 percent of the Trojans, spyware, worms and other malware in AVTest's huge cache. To be fair, that's not a bad showing by itself, and a huge improvement over Trend's performance in previous tests. Last year, the company's security suite only detected 69.3 percent of AVTest's samples.

But this year, most of the apps we looked at nailed this test with detection rates over 99 percent, and Trend Micro's improved signature-based detection rate still came in second-to-last. And it came in dead last when dealing with annoying adware, with a lowly 84.5 block rate.

Trend Micro's back-of-the-pack performance continued with a ninth place showing in proactive tests that use 2-week-old signatures to simulate detection of newer malware that doesn't yet have a signature. In these tests, Antivirus + Antispyware successfully identified only 51.7 percent of the baddies, a ninth-place showing (the top performer detected nearly 72 percent of samples). And while Trend Micro is able to identify malware based solely on how it acts, an important feature that can potentially stop brand-new malware, it isn't very good at it. Of the apps that can perform behavioral analysis, only Panda did worse.

Trend did manage to avoid falsely labeling any benign files as dangerous, and it performed well in disinfection tests, where it successfully disabled all ten malware infections. But its tortoiselike scan speeds were the slowest among the apps we tested. Data throughput for automatic scans, which happen behind-the-scenes when you open or save a file, was only 6.2MB per second.

The Japanese company's app is user-friendly, with helpful documentation, a well-organized user interface, and clear descriptions for most elements. But Trend Micro's seriously misguided attempt to over-automate the interface nullifies the aforementioned strong points.

When Trend finds a threat, its default behavior is to delete or quarantine the file without warning users of any activity. So you might end up repeatedly trying to download a file, unaware that your hard drive is being defended from a threat. At worst, you might understandably try to download and install the file on another PC, thereby infecting it.

Trend's app looks good, but in this unique software category looks take a distinct back seat to performance. And Trend's malware detection performance lags too far behind other antivirus programs to recommend.