People who hold out on installing antivirus software on their computers have lots of good reasons to do so: antivirus software can slow down your computer, it can often make a nuisance of itself if you don't choose the right brand, and so on. But sometimes, when your computer slows down or becomes flaky, you do want to make sure that it is a malware issue before you relent and buy antivirus. Some more trusting folks do have antivirus on their computer, but still have a nagging suspicion that the slowdown they notice in their computer's performance comes from overactive antivirus, and not from some undetected virus lurking in the system. For people in these dilemmas, scammers have a little special treatment in mind - rogue antivirus scanners. Let us first explain what these are, and then do an antivirus comparison - for software of the rogue variety. The rogue antivirus concept takes many shapes. And they always bear evidence of the same modus operandi. Some modify the coding in your Internet browser, and pop up what looks like a Windows system notification that asks you to do something; it is just other annoying pop-up though, that wants to make you believe it is legit. Some other lowlife attempts are occasioned by a virus infection, or an ActiveX script, and will take on the appearance of a properly installed application. Whatever they look like, they all do the same thing: they tell you that they have found a terrible virus on your computer, and will ask you to press a button to address the issue. When you do, they ask you for a small $25 donation, and then disappear with your money. One of the worst offenders is Antivirus 360, that plies its trade by trying to look and sound like software you already trust. The name itself is a take on Norton 360, and they hope you'll think that it is connected to the genuine article because it has the same number. When they pop up a window on your browser, they make it look exactly like XP's Security Center. And exactly where XP's real Security Center would have a virus protection section, right next to where the real "Recommendations" buton would be, they have a little link to buy their product. All they want to do is get your credit card number to take you for as much as they can. But a rogue antivirus comparison should bring up stuff that is a lot worse than this. Antivirus 2009 spreads mainly through spam. They put out increasingly alarming warnings with realistic-looking graphics, and when you offer to pay them for their cleanup services, they flood your computer with viruses. In a fake antivirus comparison, Win32/InternetAntivirus always has to bear special mention; Microsoft put out a special warning against this beauty a couple of months ago. Microsoft describes it this way: "A rogue program that displays false and misleading alerts regarding malware, in order to convince users to purchase rogue security software". Once you purchase their rogue security software, they install a password stealing virus on your system called TrojanSpy:Win32/Chadem that performs as promised, and steals your stuff. It is no real use keeping an eye on the websites either that these come from. They keep changing. But just in case it does any good, here are a few of the top names in the fake business: WinCleaner 2009, Malware Doctor, Spyware XP Guard, Spyware Remover 2009, Total Protect 2009/Total Defender/Total Security, Virus Shield 2009/Virus Shield Pro, and Windows Security Suite. Heads up.