Avira AntiVir Personal Free Antivirus does double duty, protecting against spyware and viruses alike. For users who want backups or want to have their antivirus and antispyware separate, we've recommended alternatives, but the trend is to find the two formerly separate features rolled into one program. AntiVir's scans are flexible, allowing the user to check all hard drives, choose a preloaded scan--for rootkits, for example--or customize. After testing on several machines, no viruses turned up, although several malicious hidden files did rear their heads. The heuristic scan can be turned on or off completely or partially, with three different intensity levels.

The quarantine offers extensive support, too, although the definition file updater can be sluggish. Still, combining effective antimalware and antivirus tools into one is a freeware luxury, and AntiVir has been rated one of the most effective defense tools by third-party testers.