BBC Bill Gates Interview Part 2: Security
Gates is right that there are a lot of malicious people (usually young dweebs with some kind of Oedipal complex against Microsoft) out there. An operating system will never be bulletproof against such attacks (just read Goedel, Escher, Bach).
The way to control it is to lock malicious hackers up for a long long time. The message has to go out that, contrary to the movie War Games, this is not a game, and you may end up in jail for ten years.
The sentence this week for one of the MS Blaster perps (18 months) was inadequate, but a start. It's not really enough of a punishment. They need to know: release a virus and ten years of your life will be snuffed out.
Vigorous prosecution put the kibosh on phreaking, and it will do so for malicious hacking too. Of course it will never be eliminated, but incarceration and social ostracism will take most of the wind out of their sails.