Thank you, Harry
I will try Win antiviruses as you adviced, and definitely will get much more concerned about security.

A little bit offtopic about viruses: The silly part of the story is that I have account with McAfee. I asked them to send me CD. They refused saying that downloading from their highly secured site will resolve problems Then I tried to download their stuff using KNOPPIX. The stupid site automatically replied that only IE may be used for downloading.
Do these guys understand what the real security is?

Thank you again.
So the outcome of our discussion about KNOPPIX is that KNOPPIX is good, but just auxiliary antivirus tool and it is not safe enough for NTFS yet. We have to live with that.