If you get virus warnings at sites like this, your computer security has serious holes. This is like leaving the windows to your house unlocked when you live in a really bad neighborhood. Even if you have a burglar alarm (i.e., antivirus program), the police may not get there in time to stop the bad guys.
To lock your windows (i.e., Microsoft Windows), you need to use a current operating system such as Windows 2000 or XP. Older versions of Windows such as 98 and ME are inherently insecure. They don't even have locks on the windows. Connecting them to the Internet is asking for trouble.
You also need to keep your copies of Windows, Internet Explorer, and other applications strictly up to date. Most virus writers don't even bother to look for holes in Windows anymore. They just wait for Microsoft to announce yet another patch, then they exploit the hole that the patch fixes, knowing that millions of people won't even bother to download the patch.
And you need to make sure that your security settings are correct. For example, if you enable web sites to download ActiveX controls, your front door is not only unlocked, it's wide open. Proper security settings are described clearly and in great detail here: