Grisoft, well known for its AVG Anti-Virus software launched its antispyware software in June 2006 under the name of Ewido. Grisoft got the technology from Ewido Networks, which it had purchased two months earlier. Now named AVG Anti-Spyware, the sleek-looking program recognized, on average, the largest percentage of adware, spyware, and rootkits we threw at it in a head-to-head competition against four other Vista-based antispyware programs. Unfortunately, its faulty behavior-based protection may not protect you against unknown threats, and it posted a high false-positive rate.

During tests performed by AV-Test.org, AVG Anti-Spyware did a good job of finding known adware and spyware. It detected 19 of 20 active samples (ones installed on the test PC)--missing only the Banbra Trojan horse, which attempts to collect online banking credentials. The AVG package was also by far the best at recognizing our large stable of inactive adware, keyloggers, bank-related spyware programs, and rootkits--a testament to the breadth of its signature database. But it failed to detect additions to HKLM Run keys, changes to the default Internet Explorer Start and Search pages, and alterations of our test system's Hosts file. This suggests that, if it fails to recognize a threat, the software may allow it to tamper with key areas of your PC. AVG Anti-Spyware was the only product tested for our October 2007 issue's antispyware roundup, "Die Spyware Die!" to produce false positives--flagging a signficant 10 of our 6285 legitimate test files as malware.

AVG disinfected spyware more successfully than it did adware, denaturing 50 percent of the spyware files and Registry entries we introduced--thesecond-best showing among the five Vista programs. In contrast, it successfully cleaned only 30 percent of adware files and Registry entries.

AVG Anti-Spyware is easy to use, with self-explanatory icons clearly marked at the top of the main interface window and with one-click buttons. On the downside, it lacks several features we'd like to see, such as antiphishing protection to prevent a user from going to known fake financial Web sites. There's no POP3, IMAP, and SMTP scanning to block e-mail borne spyware threats, either. And you can't set a system restore point in case you accidentally delete important files during a disinfection routine. Finally, Grisoft doesn't set up scheduled scans by default to help users who never delve into configuration settings.

If you opt for AVG Anti-Spyware, consider purchasing it through a third-party U.S. distributor (such as Walling Data Systems) that offers phone support. Grisoft's own customer support is limited to e-mail communications only. It's a solid program with the strongest signature database around, but it falls short in real-time protection against unknown threats.

Ryan Naraine