[roamer_1]

Depends on what you're trying to catch/avoid. It's very good at fixed-pattern matching and other lightweight techniques. It doesn't have the advanced processor=intensive heuristic algorithms of the big packages, that give them such a bad reputation for slowing your machine down.

[...] I really like Defender and its predecessor Security Essentials. But that's because all I'm looking for is lightweight protection. If I needed the more intrusive algorithms, it wouldn't be as attractive.

I hear you - and likewise would have agreed not long ago.

I would also add that MSE tends to be quite good with rootkits - not best, mind you, but it is good at it. MSE's offline/rescue scanner is competent.

But, I am a computer tech, serving residential and SOHO - My bench serves as a good study of real time 'in the wild' infections, and also by inverse extension, the effectiveness of various AV's.

By far and away, infected boxen tend to be running Norton. Second place would be a tossup between McAffee and Microsoft MSE.

Now, that is somewhat a matter of ubiquity - one would expect more of the above brands, just simply because of their wide distribution - but within my own ecosystem, that should be offset by my recommendation(s) to my customers:

I recommended F-Protect for many years, so I probably see more F-Protect protected boxes than the average, because of the effect of my recommendation (and I do, or at least, did) - Likewise, for a free solution, in a light to moderate threat environment, I had been recommending MSE (ever since AVG turned into a fat pig).

But, about a year ago, I started seeing a preponderance of MSE protected boxes coming across my bench... By about 6 months ago, I had stopped recommending it altogether. I now recommend Avast or AntiVir (Avira) as free solutions... And really, I encourage people to avoid free anti-virus...

As an aside, one might also consider that which doesn't come across my bench - My highest recommendation goes to Kaspersky Anti-Virus, with nearly as high praise going to Eset's Nod32... If people can afford it, or if they are in an high-risk environment, or if they require high security, these are the AVs I recommend.

I *never* see a KAV or Nod32 box come across my bench. And I have a lot of folks on KAV.

My own benches and server - probably the highest risk - run KAV.

[dayglored]

Yep, that list of vendors is mighty familiar... at various times I've used F-Prot, AVG, Avast, etc. Kaspersky has a great reputation, as you also attested. These days I sort-of cheat -- I only use the Windows machines for things where only Windows will do. All the rest I'm on one Linux or another, or OS X. And I stay away from dodgy sites, don't surf warez or pr0n, and mostly do actual, you know, work type stuff... :-)