Whichever version of Windows you're running (Mac users can feel smug in the knowledge that they don't need to read this) you'd be foolish to not run an AV package.
Even with the extra-secure Windows Vista operating system, viruses still pose a big threat.
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The problem is that often, most of the biggest brands that immediately come to mind when you think of AV, don't necessarily make the best software.
And likewise, you may find that a lot of the best anti-virus software is actually made by companies you've never heard of.
Either way, here are ten of the best AV packages available today.
Winner: ESET NOD32
Even though you may have never heard of it, NOD32 has consistently been voted the best anti-virus package by experts and users alike.
Just this month, it was awarded a record 51st VB100 award from Virus Bulletin, a respected independent comparative testing group.
It's also been named the best AV package by AV Comparatives for two years in a row.
Not only is NOD32 an extremely lightweight piece of software, it scans very quickly, has faultless heuristic detection (it can detect a virus even if a definition has not been written for it yet) and can be relied upon to detect 98 per cent of computer nasties.
Based in Moscow, Kaspersky has now been protecting Windows PCs for over ten years. It always rates in the top five AV programs in independent tests, which makes it a viable option.
AV comparatives fives it an Advanced+ rating (the highest possible) because of its 98.3 per cent success rate in virus detection (most recent tests).
Kaspersky is one of the most popular and fastest growing anti-virus programs around and should be considered an excellent security option.
F-Secure has an excellent record at detecting viruses and other internet nasties. However, to achieve this, it's fairly slow at scanning. And it also returns quite a lot of false positives (it sees threats in places where none exist) which can make it a bit confusing.
If you're looking for a maximum amount of protection, F-Secure is for you. But if you need smooth and speedy operation with accurate threat detection, it might not be ideal.
It includes a behaviour based/HIPS-like solution which works when malware is executed.
This kind of protection is not taken into consideration in the AV Comparatives tests at present, which is why F-Secure doesn't fare too well in the heuristics test. However, that's not to say it's a poor performer. Because it's not.
And this will show up when the site starts including this kind of pro-active screening in its 2009 tests.
AVIRA AntiVir PE Premium
AVIRA's anti-virus program is one of the favourites on AV Comparatives. In the most recent tests, it managed to successfully detect 99.6 per cent of threats posed while returning few false positives.
As a consequence, it's one of only two packages (along with NOD32) which achieved an Advanced+ rating on AV Comparatives in its proactive/retrospective test.
GDATA is a very handy anti-virus package which uses the AV engines of both Kaspersky and Avast. As a result if achieves a very high success rate at detecting known viruses.
However, its heuristic detection is poor, and doesn't even rate on the AV Comparatives league table.
AVG gets an Advanced+ rating for its detection of known nasties. And its heuristic 'in the wild' detection is also good. It's not up to the standard of NOD32, but it's a viable option.
It's worth pointing out that this is not the free version of AVG - which offers only very basic virus protection.
Symantec Norton 360
Symantec's Norton Anti-Virus program is possibly the most well-known - certainly in the USA. However, that doesn't make it the best.
If you've already got Norton though, worry not. Because virus protection is up there with the best - especially from known threats.
Its heuristic protection, on the other hand, is distinctly average. It doesn't perform as well as the likes of Kaspersky, AVIRA or NOD32 in this respect. Norton also tents to return a fair amount of false positives which can cause confusion.
McAfee VirusScan Plus
Another household name is McAfee. It's one of the best known names, and it's also currently one of the best. It's detection rate, scan speed and heuristic detection are all pretty good.
Although you cannot say that McAfee is in any way state-of-the-art. It's just a solid all-round performer.