Norton indicates that it should easily remove the virus "killAV" if definitions have been updated since October 2006, but there is a "trojan" form using the same name that may be more difficult, and definition files for it were updated fairly recently.

You might want to take a look at Trojan.killAV Removal to see whether there might be some Registry cleanup you need to do, in addition to just deleting the file.

The technical details suggest that this is spread by someone looking for, and finding, an open port on your computer through which they can download it without your participation. You might want to try Norton's "Security Scan" which will probe your computer to see how "visible" it is, and will tell you if you've got something hanging out, and what you could zip up to avoid exposing yourself.

John