Hi, yep the virii is plural for all the viruses. Gosh, I remember when there were just 300 of these things out. And F-Pro was free. F-Pro at the time was the BEST! Well I think it still is for DOS. A few links that may be of information to you:

Trojan Horses:
Technically, Trojan horses are not viruses because they do not self-replicate (make copies of themselves). But, like a virus, a Trojan horse is "a program that performs some unexpected or unauthorized, usually malicious, actions such as displaying messages, erasing files or formatting a disk." (Wiederin, Hoefelmeyer and Phillips). To get rid of a Trojan Horse simply delete the program from the computer.
< I just love how they say simply delete the trojan from the PC.>

http://computer.howstuffworks.com/virus.htm

http://www.bris.ac.uk/is/services/computer...us/how_work.htm

http://www.slais.ubc.ca/courses/libr500/02...uk/How_Work.htm

I still don't really understand in depth how these all work. I know have wanted to throw the PC out the window ever since windoze has come out. Still have plain ole emulator of a windoze on my PC that is for DOS. Have had it way before widoze has ever come out, and I wish it never had. Saw the first demo of windoze at the college BBS group. I wasn't impressed. Miss the days of ASCII, DOS, BBS's.
--K.N.--

Heres some links may help you out.

Virus Glossary - From F-Secure

Sophos White Papers

Year of The Worm

I have to say i agree with you i remember the days of the bbs and dos.....and ascii... OMG ascii art ruled i helped run a bbs called Roast Duck anyhoo i miss those days and i hated windows back in the begining and still do however it seems to be the way of the world now... i hope to move into linix soon myself although i know that windows will continue to be the primary os that i have to use since i love my games...