Wow! That is the most elaborate version that I have ever seen. An unknowledgeable victim would be more likely to send money to these people instead of one that is just a single flashing pop-up with, "Your Computer Has Been Contaminated! Send us $49.95 to get it fixed!!!!!".
Another that I have seen, that was on my friend's computer though she swears to me that she never "downloaded and installed anything", is called AntiVirXP08. It is small and looked somewhat authentic as it ran a scan and found threats on her computer. One thing that made it an obvious fake was that the full scan of her computer happened too quickly, found a large number of threats, but gave no idea what files were infected. Like the version described in the article above, it gave us the options to continue without cleaning or to remove the threats, but to remove them she would have to pay. It also had a system tray icon that popped up warnings regularly.
Although removing it was not difficult, this particular malware played a few additional tricks that spyware/malware removers do not detect because they are technically not malware issues. After "scanning" her system, it changed the background wallpaper to one that mentioned having serious threats on the computer. It also changed the screensaver to a Windows XP Professional loading screen (she uses XP Home, so that was an obvious flaw) and after trying to escape the screensaver the first time, an authentic looking BSoD appeared, but another button press exited out of it since it was still only a screensaver.
The biggest problem was that once the malware was removed, the screensaver and wallpaper remained and extra steps had to be taken to get rid of them because the virus also changed two registry values removing the Desktop and Screen Saver tabs from her Display Properties menu. Since it would load on startup and both the program and the background image are used as constant remuinders that there is a threat on the computer (even though it is fake), I can understand how this could easily scam certain people into a purchase.