“Scareware,” or programs that masquerade as legitimate security and anti-virus software and then frighten and bully users into paying for them, have emerged as the most prolific and fastest-growing threats facing PC users, according to a biannual security report released this week by Microsoft Corp. George Stathakopoulos, general manager of Microsoft’s trustworthy computing group, said these rogue security products can snare even experienced computer users. “Some of these sites and products look really professional and well-done, with trademarks and copyrighted material,” Stathakopoulos said. “If you’re in a situation where you don’t already have security software and you have not yet figured out the state of the machine, you will look for a solution, and these are solutions that come to you.” Microsoft found that in the second half of last year, seven of the top 25 malicious software families removed from Windows computers were scareware titles such as Antivirus2008, XPAntivirus,