dklynn, two or three years ago Consumer Reports did a review of antivirus programs. One of the most important points they made was that no antivirus program is 100% effective. 70% to 80% effectiveness in detecting malware was the figure they stated, if my memory serves. As Consumer Reports is a subscription service, they don't offer that information on their website. My parents have a subscription and I asked them to keep that particular issue with the antivirus ratings on it. I'll contact them and see if they still have it. If they kept it, I'll scan it for you so you can see it for yourself.
The point I am trying to make is that despite popular misconception, no antivirus program is anywhere near perfect at detecting viruses and other malware. I argue with people about this all the time. People mistakenly think that if they are running antivirus they are completely protected and nothing could be further from the truth.
And even if your virus detection success rate figure of 90% was true, that's still pretty poor. If there is a 10% chance you are going to get run over if you cross a road, will you attempt to cross it?
Consumer Reports ranked the following free antivirus programs highly (I think in this order):
Microsoft Security Essentials
I have used all of them. Microsoft Security Essentials is really the only one that works acceptably on an older computer.
Sure, the detection rate for a 10-year-old virus may near 100%. What about a new virus created yesterday? Last week? Two weeks ago? Last month? Virus writers are always coming out with new ones. Not many people are still trying to infect computers using the 2001 Code Red worm, are they?
As for newer virus detection rates:
The Effectiveness of Antivirus on New Malware Samples
December 21, 2009 at 12:00 pm PST
Of the relatively new malware specimens only 40% (62 of 152 samples) were detected by more than half of the antivirus products, while about 60% were detected by less than half of the products. A little over one quarter of the samples (28%) were detected by less than 30% of the antivirus products, which is an alarming statistic.
The overall detection rate near the day of detection for these samples was 18.6% and that improved to 62.9% one week later.
end users should be on guard because the likelihood that an antivirus product will save them from poor decision making is less than 50%.
Bottom line: no antivirus program is going to save you from yourself. Never download and install software from an untrusted source. And avoiding shady neighborhoods like pr0n and warez is always wise.
And if you want to dredge up stuff from 2007:
You see, I do my research.