According to Pandalabs more than 111,000 bogus antivirus (or other anti-malware tools), so called scareware, have been discovered in the first quarter of 2009. This is more than what was discovered in 2008 in total!
Before downloading and using a tool that claims to check and remove a virus it is advisable to do a check against one of the white lists, to see if the vendor is reputable. Otherwise the tool might infect the computer that it has been installed on.
Here is a link to a whitelist page: Antivirus Vendor Whitelist
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