As in many replies in this forum, you probably have a load of adware and spyware onboard.  These are not detected by anti-virus software.  Get either/both the following and run.

Spybot - http://security.kolla.de/

Ad-Aware - http://www.lavasoftusa.com

(addresses courtesy Volcano11's post!).  If you have not run before, you will probably get several hundred items.

The former site just had a DOS attack but they are up running again.

The worm you mention is on the NAV "top ten".  From your original post it seems you do not have permanent anti-virus as you went to the NAV site to do a check.  I think NAV has been sending auto updates about one a day so that's how quickly you need protection.  Anti-virus and a firewall are essential and their cost is part of "doing business".  If you are just getting an occasional check, you are almost certain to get infections.

If you do not completely understand the removal instructions at NAV site, get someone to help.  They can be confusing.

According to Symantec site it will be in the live updates on 14 April, but in fact it is included in the 12 April live update (just checked the what's new file in C:\Program Files\Common Files\Symantec Shared\VirusDefs\20040412.008).

Also, it seems to come in through a port, it is not from e mails as so many are. Do you have a firewall? If not Zone Alarm (free version) is recommended by many people).