By staring at this page for 30 seconds, setting the security level of IE to medium, then agreeing to download the ActiveX control, your computer will get measles (or Web Measles) to be more precise.
The page and control demostrate the danger of ActiveX controls, although mine simply paints on the screen with no other side effect (although if you don't download it, I cannot blame you at all!)
To stop the infection simply select a new web page or close IE.
After this experience, you might decide to disable ActiveX in your browser. If your browser is Netscape, you don't have to worry, you won't get measles
.
For your information, Web Measles was build with Delphi 3 in about 15 seconds, using the ScreenVirus component. Consider what one can achive with a little extra time...