Doesn't everybody know that virii is a non-word? The plural of 'virus' is 'viruses'.
I quote from http://www.perl.com/language/misc/virus.html
Those confused souls who write *virii are tacitly positing the existence of the non-word *virius, and declining it as though it were like filius. It's true that l/r are both linguals that sometimes get interchanged, and that f/v are just a change in voicing, but that's just reaching. *Virii is still completely silly, so don't do that; otherwise, everyone will know you're just a blathering script kiddie.
An open, cross-platform journaling program.
A scientific plotting package.