Hmm..... Viruses...
Someone asked me: "why don't virus scanners stop all the viruses?"
Well, its quite simple... Firstly someone has to get the virus, "capture" it and then debug it to write an antidote... Same way real a virus works !
"So how is a virus checker supposed to know when the new bit of code is a virus?"
Because it recieves updates from the company that created the virus scanner, and then your pc can be "imune"...
So there is a few questions answered for you.
However !!!! a firewall is NOT a virus guard. It is a hacker guard. A virus is software that attaches to another file, or is its own file that is downloaded, sent via e-mail or runs from a website. The firewall will only protect the pc from breakout code from when your pc is attacked or is trying to attack with a barage of e-mail.
The best option is to have a hardware firewall (built into the router), a software firewall, a virus checker, and some ad/spy ware remover.
This is how i have been running for 3 years, and i have only ever had 1 virus which was promptly removed... I do have various attacks on my web site, but no one has succeded in getting into my network.
Hope this is of some help...
By the way: the lastest virus table is
here.