I wonder how it got on my machine since I use Norton and it is up to date.
1) It's not a virus in the traditional sense.
2) Norton or any other virus killer has no way of stopping new viruses and worms. The virus/worm need to be captured, analyzed and finally detection and removal code written for it. This is very specialized handwork and cannot be made automatic, so it takes time.
With the today's fast spreading distributed worms and exploitable windows holes it's almost impossible to get generic solutions against such things. If you want to be safe, get rid of Windows. Or at least run real firewall (NO, windows built-in firewall is no solution here).
One upto-date hardware firewall or a linux/bsd box routing all traffic should be enough to stop 99% of the baddies.
