Avast! Free AV security An anti-virus solution for Windows that's free, respects your personal privacy and doesn't get in your face? I'm currently trialling Avast! Free, a free-to-download package from Alwil Software. And historically, Avast! is also rated well in AV group tests. The only drawback I've seen so far is the daft Yahooesque! exclamation mark in the name...

Depending on how you measure it, most anti-virus software is at least 90% effective against the majority of virus, Trojan and worm threats. That figure drops significantly, though, when you include the most up-to-date flavours of malware, the stuff that's updated daily by the eager developers.

When you're relying on heuristic detection - the 'braces' after signature detection's 'belt' - AV software's efficacy can drop to 60% or less. Which leaves you with about the same chance of avoiding infection as if you flipped a coin to decide the outcome.

Heads you're clean; tails, your PC is owned by a hacker the other side of the world.

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So once you accept the Russian roulette world of Windows security, you need to take a long hard look at all the other aspects of AV software that you choose to install on your Windows PC.

How much will it slow down my computer? How much longer will it take my PC to boot? How often will it get in my way during routine use, with pop-up messages to tell me what it's doing? And if it's a free AV package, how much will it advertise at me, or constantly nag me to cough up for the paid version?

Family Tech Support

Helping the family recently with some AV security for their Windows box, I was looking around for a competent, lightweight and free package. Free, not just because of the enticing no-cost factor, but in order that protection wouldn't fall off even further the moment the subscription expired in one year.

After a quick dig around, I thought I'd give Avira a shot. Its efficacy seemed quite good, based on the usual suspects' lab testing. But I hadn't figured on the amount of full-screen advertising, entreating you to buy the full version. Personally, nothing turns me off anything quicker than unwanted advertising.

Avast! virus decoration

Avast!'s new headquarters in Prague features virus code as door decorations

So I've been that much more impressed to discover another long-standing AV package which seems to do its damnedest to stay quiet and ad-free. It's the new v5 version of Avast! from Alwil Software in the Czech Republic.

And unlike some free packages, it doesn't seem that hobbled by feature cuts. Or insist that your PC is monitored with 'anonymous' information quietly sent off to the maker's servers, as with Microsoft Security Essentials.

The company's business model is interesting, nonetheless. Of about 105 million active users, 97% are using the free version. So Alwil makes its money from those that do pay, including fees from various commercial versions it sells.

There's also a little hint to download and install Google Chrome when you first install it, for which Avast! gets an unspecified kickback.

But those users that opt in to the program's community watch system are actively helping identify new threats, upping the efficacy of the software for the benefit of both the company and all other users. And thereby raising the value of all Avast!'s property, its security programs. So the vast number of Avast!'s free users are unpaid watchdogs, but ones who are rewarded with free protection.

It remains to be seen how well the just-released version of Avast! Free scores in lab group testing, but it certainly looks well rated in previous VB100 and AV Comparatives tests.

In the meantime, I'm enjoying the relative peace and quiet of discreet AV software on my Windows 7 machine. And hopefully, once we've upgraded her, so will my mother-in-law too.