Free security tools !

Yes, that's "free" as in "free beer". Some of them may also be free as in "free speech".

Commercial antivirus products and "Internet security suite" software are not cheap to buy and incur annual running costs of £20 - 40 to keep receiving regular updates. They have also acquired a reputation for creating instability or performance problems especially on older machines with less RAM memory or slower processors. Even Norton think their 2006 product is rubbish.

By using free products you obviously avoid the cost, but you are also free to change to a different product if you run into problems without feeling that you are throwing money away.

In tests the free products can be as good or better than the expensive versions in boxes on the shelf at PC World, so you aren't taking a big risk by opting for the free versions - most of them are based on commercial products but have some restrictions.

Google offer a pack of free tools and software to download. Every PC user should consider
having StartupCPL installed to turn off those pesky things that start up when you don't need them.


Antivirus.

AVG Free - very popular, defaults to virus scanning daily although you can change the time it runs.

Avast! - only scans when you tell it to, but updates regularly. Requires registration via email.

Comodo - a new product but if it is as good as their firewall definitely one to try.

Clamwin - open source hence free as in speech as well as free as in beer.

Avira - Works with Vista & XP, slightly annoying advert page after updating database.


Greyware.

Tools to address things that aren't really viruses but you don't want them anyway.....

Spybot S&D - particularly good with Trojans which the likes of McAfee detects but never remove.

Ad-Aware - spyware removal. If your getting popups or other issues run this then Spybot S&D.

AVG Antispyware - formerly Ewido, specific tool for spyware removal.

Spyware Doctor - this isn't free, but you can download it for free and scan to identify problems. Google Pack currently offers a free version of Spyware Doctor, you can select only that or add other free software from the pack.

TrojanHunter - 30 day free trial.

SuperAntiSpyware - often recommended on forums but not one I personally lke - perhaps the childish / gimmicky interface puts me off.

MalwareBytes AntiMalware comes in free and paid -for versions. The free one is good for cleaning up infected machines and the paid version adds a level of continuing protection.

The above tools can be used to clean up a computer and then be removed, or in some cases they offer an ongoing "protection" to your system - this will use up some memory etc.


Firewall

If your PC connects to the internet with a USB modem then a good firewall is a must, as your PC has an externally accessible IP address and can be attacked from the internet. If you have a router then your PC is much safer as it has an internal IP address not accessible from the outside, and most routers have some form of firewall built in.

Windows XP, Vista and Seven / 7 have firewalls built in, so the minimum is to use those where appropriate. The XP firewall is incoming only and you have to turn on the outgoing firewall settings in Vista / 7. Macs and Linux machines have software firewalls as part of the operating system, again this may need to be turned on or configured initially.

Comodo - comes out well in "leak tests", stops malicous outbound or inbound traffic. Vista/XP.

Online Armor - a free version of their firewall is available.

Jetico Personal Firewall - a mature product that still does well in tests and supports Win98/ME 

Sunbelt Kerio - the free version is effectively a trial version of the full product.

ZoneAlarm - another popular one. Difficult to turn off if you're trying to diagnose a problem.

When operating in a secure mode firewalls will ask your permission to allow new programs to access the internet, you can usually tick a box to remember the setting but if you turn off these warnings altogether you may allow unwanted traffic. Similarly answering "yes" to every firewall warning without thinking about it could also allow bad traffic to pass.


Note all of the above are free products however some of them may install as a 30 day trial of the full version and ask you to pay at the end of the trial period. If you don't pay the functionality is reduced to that of the free version and you can keep using it, or if you think the extra features are worthwhile you can of course opt to upgrade and pay for the full version.