>A real viri has to accompany it in order to 'extract' the payload, so what's the point? The viri may as well pack its own payload.

Jerry
Just as an aside here, "viri" is the plural form of "vir" meaning "man" - in Latin "virus" was a word a bit like sheep - it was used unchanged in singular & plural form. These types of words from latin tend to use "-es" to denote the plural, so "viruses" is the correct plural form of "virus". (At least in English English, American English may of course be different - I've had that discussion before).

http://www.perl.com/language/misc/virus.html
http://homepages.tesco.net/~J.deBoynePollard/FGA/plural-of-virus.html