As you guys might remember, I had (have) a spam bot on one of my networked computers. My outgoing emails were blocked by some self appointed god. They said the only way they would unblock my computers was if I disinfected my machines or blocked my outgoing port 25. I hope I have blocked that port because I am able to send email (for the time being). However, relevant to this discussion, I wish to quote a very small section from all the "what to do, they sent me".
"Running a combination of anti-spyware and anti-virus programs should
> help to find the malware.
>
> It is unfortunate, however, the track record of current/popular
> Anti-Virus software at finding current and severe threats is abysmal.
> In fact, recent studies have shown that "new" threats are only caught by
> _any_ of 35 of the most common A-V packages 23% of the time, and that
> only improves to 50% after a month. In other words, if you were running
> ALL of those 35 A-V products at once, a new threat would be caught only
> 23% of the time by _any_ of them."
So, good luck!
FWIW
George