If you can get to the internet, start with housecall.trendmicro.com and see if you can at least get a name for the virus as to which one you have. If you cannot get to the internet, the easiest thing to do at that point would be to find a second, working computer you can borrow, make sure that computer has all it's service packs and antivirus files up to date, and then remove the hard drive from the infected computer, set it to slave mode, and pop it into the working computer and use the working one to clean the drive.
Alternativly, you can download the latest norton virus defininitions on another computer, transfer them in on a disk to the infected one, reinstall antivirus and update the virus definitions before the virus can kill norton again.
Sounds like you have a fairly nasty one there. If you can get me the name of what type it is, I can give you more detailed instructions for killing it.