Heh... yeah, sending out virusses would be very bad business, so your dad can rest assured that VSTEP would never do such a thing, nor would any other company that has to make a living off those products.
In fact, you're thousands if not millions of times more likely to get virusses from day to day internet stuff like emailing (if you're daft enough to open up questionable mail), using chat programs or surfing to unreliable websites, not to mention downloading stuff. I trust you have downloaded the patches over time.. so doesn't your father feel the same way about those? Because his view could apply there too then. The truth is, companies don't send out virusses in their products. Hmm.. well at least, VSTEP is not... Microsoft, now that is another story.. their mnain product IS a virus.. (I know it's got me pretty sick from time to time)
Perhaps your Dad isn't all that computer literate, I don't know, and I don't mean any disrespect of course. I know mine is skeptical about online shopping or -banking etc aswell. Perhaps you can persuade your dad by showing him some facts about such things in reliable media...
Fred