That's a hoax you've dug up there Broni.
http://www.sophos.com/security/hoaxes/virtualcard.htmlWhen the ctrl+alt+ del keys or the reset
button are pressed, the virus destroys Sector Zero, thus permanently
destroying the hard disk
A virus can't destroy a hdd sector, it could at most overwrite it. If it overwrote the first sectors it would make your computer unable to boot but in most cases this could easily be repaired without any loss of data by reinstalling the boot loader.
Boot sector viruses are btw. probably the oldest type of virus and is all but extinct today.
I think the question about 'the worst virus' is impossible to answer without a more precise definition of worst.
To my knowledge, no virus have yet done any unrecoverable hardware damage. The only one that have come close was the Chernobyl virus that could wipe the BIOS on some motherboards. But even then the BIOS could simply be reflashed and the computer would be up and running again.
So if you by worst, mean most damage to a single computer the title will go to all the viruses that have tried to delete data. I'm guessing this is well over a 1000 viruses.
If you by worst mean the virus that have made the most damage in term of money (i.e. loss of revenue, productivity, cleanup and so on) the title probably belongs to the ILOVEYOU worm. (Which technically isn't a virus at all). It is estimated the total cost for businesses was upwards of 5 - 10 billion dollars.