As if keeping viruses from your computer isn’t hard enough, there are new reports that tens of millions of people might be installing fake antivirus software that doesn’t protect their computers, installs its own viruses and charges the unsuspecting user for the privilege.

One Anti-virus company found 1,000 samples of fake antivirus software in the first quarter of 2008. A year later, that number had grown to 111,000. And in the second quarter of 2009, it reached 374,000.

The rogue antivirus software typically issues false warnings of infections in order to get people to pay for software they don’t need. The programs also typically download a Trojan or other malware. The U.S. Government task force on computer crime estimates there could be as many as 35 million computers infected per month with rogue antivirus programs.

About 3 percent of the people who see the fake warnings fall for it, forking over $50 for an annual license or $80 for a lifetime license, according to official estimates.

Last September, a hacker was able to infiltrate rogue antivirus maker Baka Software and discovered that in one period an affiliate made more than $80,000 in about a week.

A Finjan report from March estimated that fake antivirus distributors can make more than $10,000 a day.

After all the hoopla about the Conficker threat, researchers seemed almost relieved that it turned out to distribute fake antivirus software instead of something much worse.

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