Local Computer Guy

Free antivirus software, like AVG Free, Avast Free or Avira Free offer good but very basic level of protection, not even close to what you really need.

 Appx. £30/year spent on a proper Internet Security software really makes a difference.

Malware definitions from Kaspersky Lab UK (http://www.kaspersky.co.uk/threats_faq)

What is MALWARE?

Malware - short for malicious software - is an umbrella term that refers to any software program deliberately created to perform an unauthorized and often harmful action. Viruses, backdoors, keyloggers, password stealers and other Trojan horse programs, Word and Excel macro viruses, boot sector viruses, script viruses (batch, windows shell, java, etc.) and Trojans, crimeware, spyware and adware are but a few examples of what is considered malware.
It was once sufficient to call something a 'virus' or 'Trojan horse', but infection methods and vectors evolved and the terms virus and Trojan no longer provided a satisfactory definition for all the types of rogue programs that exist.

What is SPYWARE?

As the name suggests, this is software that is designed to harvest your data and forward it to a third party without your consent or knowledge. Such programs may monitor key presses ('keyloggers'), collect confidential information (passwords, credit card numbers, PIN numbers, etc.), harvest e-mail addresses or track browsing habits. In addition to all of this, spyware inevitably affects your computer’s performance.

 What is ADWARE?

Adware is the general term applied to programs that either launch advertisements (often pop-up banners) or re-direct search results to promotional web sites. Adware is often built into freeware or shareware programs: if you download a freeware program, the adware is installed on your system without your knowledge or consent. Sometimes a Trojan will secretly download an adware program from a web site and install it on your computer.

Web browsers that aren’t up-to-date often contain vulnerabilities. Such browsers are vulnerable to hackers tools (often referred to as Browser Hijackers) that can download adware to your computer. Browser Hijackers may change browser settings, redirect incorrectly typed or incomplete URLs to a specific site, or change the default homepage. They may also redirect searches to pay-to-view (often pornographic) web sites.

Typically, adware programs do not show themselves in the system in any way: there will be no listing under Start | Programs, no icons in the system tray and nothing in the task list. They seldom come with a de-installation procedure and attempts to remove them manually may cause the original carrier program to malfunction.

 What is a TROJAN and where did the name come from?

The term Trojan refers to the wooden horse used by the Greeks to sneak inside the city of Troy and capture it. The classic definition of a Trojan is a program that poses as legitimate software but when launched will do something harmful. Trojans can't spread by themselves, which is what distinguishes them from viruses and worms.

Today, Trojans are typically installed secretly and deliver their malicious payload without your knowledge. Much of today’s crimeware is comprised of different types of Trojans, all of which are purpose-built to carry out a specific malicious function. The most common are Backdoor Trojans (often they include a keylogger), Trojan Spies, password stealing Trojans and Trojan Proxies that convert your computer into a spam distribution machine.