I'm using Norton 2002 with 'Live Update' set which keeps it up-to-date. I used to have PC-cillin, but switched to Norton when PC-cillin failed to pick up a particular virus. (This wasn't the latest version of PC-cillin although I was receiving regular pattern updates.)
I also have the free version of ZoneAlarm installed and it is suprising how often it blocks an attempt from someone (or probably some system) trying to get into my PC.
My daughter and her husband were asking me about getting an internet connection for their computer, and I told them they must budget for anti-virus software. It is unfortunately essential, and a firewall like ZoneAlarm is also advisable.
Mike