There are excellent free-of-charge anti-virus solutions available:
AVG offers full anti-virus protection including email attachment scanning. To obtain the software you must fill out a registration form and wait to receive an activation code in your email. The software regularly wins awards in PC magazines for its quality and value. Some users have reported problems actually downloading the program however. It can be annoying to go through a long-winded registration process but then be unable to download the software at the end of it! No technical support is provided for the free version of the software.
To obtain the software, simply click the "download" link on the left and then on the "AntiVir" graphic. You are not even required to register the software or to provide any personal information. Excellent free technical support is provided in the forum. Although the company is based in Germany, the forum is bilingual, and many users have reported that help is quick in coming and efficient. I personally recommend this software, having used it since an early version. It is fully featured, including a task scheduler and email attachment scanning! The name given to the actual scanner application ("Luke Filewalker",) still tickles me every time I see it!
It should be noted that both the free products mentioned above are licensed for personal use only.
In addition to these free downloadable virus scanners, there are also a number of websites which offer free online virus scanning over the Internet.
This is an excellent scan which is guaranteed to be fresh as the virus database is updated daily. You have to give an email address but can easily unsubscribe from the company's occasional mails if you wish, (though they are actually a useful source of genuine early warning virus alerts.)
This online scanner is a demonstration of Trend's corporate distributed scanning technology. It is no less useful for it, though it takes some time to download initially.
A firewall can be a piece of software or a dedicated hardware / software combination. Firewalls are designed to plug the security risks associated with open ports. They do this by:
Most firewalls allow a degree of customisation so that you can, for example, tell your firewall to always allow data to flow to and from regularly used applications such as Internet Explorer.
A software firewall sits on your computer and polices your computer's communications with the world outside. Whilst a software firewall is adequate for most home users, it can only be as secure as the Operating System it runs on. Hardware Firewalls are also available and are considered more secure.
The most popular Windows firewall. Whilst the free version does not offer quite as many features as the Pro version, it's free-of-charge and quite sufficient for most users, especially when used in conjunction with one of the free virus scanners mentioned above.
Spyware removal software works in a similar way to a Virus Scanner. They scan your computer's memory, Registry and disk drive(s) for spyware, adware and other unsavoury software. Having informed you of what they have found, they can then proceed to remove it from your system. Some can also "quarantine" the spyware so you can restore it later if you wish (the definition of spyware and adware is not 100% clear-cut and some software which the scanner defines as spyware may in fact be useful to you. The Alexa toolbar is a good example of this - whilst it collects data on your Internet use and is therefore technically spyware, most users feel comfortable about trusting Alexa's privacy policy - the company is after all owned by Amazon.com! - and find the website ranking and popup-stopping services which the toolbar provides to be very useful.) Many file-sharing programs install adware as part of the End User License Agreement (EULA.) This allows their developers to provide their complex software for free without directly charging the user to download it. Instead they charge the various advertisers to popup their advertising messages on your machine. Sadly many online advertisers haven't yet realised that "interruption advertising" is more likely to annoy the recipient than to persuade them to immediately buy their product!
Removing some adware may prevent your file-sharing programs from working. A Spyware removal tool should be used to complement a Virus Scanner and a Firewall - it replaces neither but adds an extra level of security to your PC.
There are also a number of genuinely free Spyware removal tools available:
Probably the best spyware elimination software on the market (it recognizes far more rogue programs even than the market-leading adware programs).
it is "donationware", and even if you choose to give a voluntary donation to the author, it is still truly excellent value.
The Alexa Toolbar for Microsoft Internet Explorer comes with a popup stopper.
The irony with this solution is that every time a website tries to popup a new window, the Alexa toolbar gives you a little popup message saying "abc website is trying to launch a popup, do you want to let it?" This is not quite as ridiculous as it sounds, however, as you only get this message once per site.
The Google Toolbar comes with an Auto-fill feature (allowing you to store details like your name and email address to add them quickly to a web form,) and also allows you to search the web directly from the toolbar.