often virus writers see it as a challenge, a chance to show off their good programming.
if they can write a virus which can get into millions of computers, past all forms of computer security then thats something.
i dont think a "virus" can be used for good. virus is bad hence the name. a good virus is just a good program. this can be interpreted a lot of ways, but thats the way i see it.
i mean say you had a "virus" which spread and all it done was defragment someones drive. i guess it could be classed as a virus because it spreads without the users consent, but it doesnt do damage, its actually doing good. just depends on the persons interpretation of a virus.
--- Every man dies, not every man really lives ---