Dr. Web helps you minimize contact with unsanitary files before you download them, by scanning them in advance and letting you know before it lands on your desktop if the file has a clean bill of health or if you should put on your biohazard suit before handling the innocuous-looking critter.

Available for Firefox, Internet Explorer, Opera, and Mozilla's Thunderbird, the free Dr. Web Anti-virus Link Checker extension adds a context-menu option that scans files for viruses before you download them. The program opens up a new window, and even with a 400 MB file it took about 15 seconds to return a green-themed "Clean" window for a virus-free result. The red-tinted "Infected" pops up if you're about to perform some risky behavior.

Dr. Web quickly responds with a pop-up indicating whether your download is virus-free... (Credit: CNET Networks, Inc.)

After checking dozens of download links on sites known for being both safe and dangerous, the link checker picked up potential virusware only in places I was expecting to find it: on free game sites, free ringtone repositories, and the like. This, of course, proves nothing. The extension works by linking directly back to the publisher's servers, so there's no risk because you're not downloading anything.

If the Dr. Web publishers haven't made the most recent updates to their definition files, then the plug-in isn't going to catch any newly-created viruses and you could be ground zero for the latest worm going around the block. However, the main app's been around since the mid-1990s, and they seem to take their updates very seriously. It's good to see that the Dr. Web folks have made the extension cross-functional with Thunderbird, since downloads are sent in e-mails. Shocking, I know, but there it is.

...or infected with a virus and probably something you should avoid. (Credit: CNET Networks, Inc.)

One thing to keep in mind with the link checker is that it's designed only to check for viruses and it's only meant to work with downloads. If you download a file and it's got some other form of malware hidden in it, don't come to me with your malpractice claims. Still, the practice of getting users to think about what they're downloading before they make that potentially fatal click can only be a good thing, limited as Dr. Web is.

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